Frank J. Merli and
Robert H. Ferrell
Blockade, historically speaking, has been a maritime measure, to restrict entrance to a harbor or its environs. The word has been stretched to include entire countries. Sometimes "blockade" has meant enforcement or threat of enforcement by land rather than by sea, along the borders of an opposing nation or nations. The blockade has always been an attractive concept to the American people and government, for it has been seen as a way of restricting war and even of preserving peace. In time of war, a narrowly drawn blockade might ward off a conflict and allow a neutral nation, perhaps the United States, to carry on its trade much as before. In time of peace, a blockade might prove sufficient to discourage a quarreling nation from employing military force. According to international law there can be pacific as well as belligerent blockades, but most, of course, have been instituted in wartime. Although other terms—"quarantine," "interdiction," "interception"—have gained currency over the years, the basic concept of blockade has remained an important component of American diplomatic and military policy.
DEVELOPMENT OF THE LAW
The law of blockade, that is, the rules governing proper legal practice, originated in the early struggles for supremacy among the maritime nations of Europe in the fifteenth and sixteenth centuries. During that time, belligerents hacked and hewed, by sea as by land, and neutrals constantly found themselves involved in quarrels, whether they wished to be or not. Early in the seventeenth century a compromise of sorts emerged between neutrals and belligerents, in which the latter undertook to define carefully the list of items that were contraband and subject to capture. They also agreed that blockades could not merely be proclaimed: acceptable practice required that a port be cordoned off by the stationing of naval vessels at its entrance. As originally conceived, a blockade was a maritime equivalent of a land siege. When a port was properly blockaded, an investing belligerent could prohibit all trade with that port, including that of neutral nations. The idea apparently appeared first in a 1614 treaty between the Netherlands and Sweden. A refinement of the concept of effective blockade appeared in a Dutch announcement or Placaart of 1630, issued after consultation with private jurists and judges of the courts of admiralty. Its first article declared: "Neutral ships and goods passing in or out of the ports of the enemy in Flanders; or being so near them, that there can be no doubt but they will go into them, shall be confiscated: Because their High Mightinesses continually beset those ports with ships of war, in order to hinder any commerce with the enemy." Interestingly enough, the drafters of this rule justified it as "an ancient custom, warranted by the example of all princes"—a useful, if not entirely accurate, assessment of prior practice. The "law" of blockade, however, unlike other branches of international law, owed less to statutory enactments and more to the customs and precedents of naval officers and admiralty lawyers as they sought to bend the definitions of blockade to accommodate national interests, especially the need for victory in war.
In the early modern period of European history, with its frequent maritime wars, new rules of blockade rapidly evolved, and as they grew they acquired increasing importance as effective instruments of naval coercion. But those rules never remained static. They required frequent adjustment to new circumstances, technological innovation, and modified strategic concepts. More importantly, over the centuries, blockades had to be adapted to the exigencies created by new definitions of the nature of war.
From the mid-seventeenth century onward, new concepts of blockade were developed, and soon the nations of Europe agreed on some basic rules governing their use. Hugo Grotius, the father of international law, set out a rule that foodstuffs, so-called provisions, should be treated as contraband only when an attempt was made to introduce them into a blockaded port in extremis, and this humane refinement received general approval from naval authorities. For their part, legal theorists such as Cornelis van Bynkershoek generally agreed that international law recognized no right of access to ports effectively closed by naval squadrons. When the United States drew up a model treaty of commerce in 1776 for submission to foreign nations, it overlooked an article defining blockades, but soon remedied that omission. American statesmen took inspiration from the attempted Armed Neutrality of 1780. Catherine the Great sought to bring together some of the European neutrals in the general war then raging, to unite them in a pact of armed neutrality that would enforce an expanded definition of neutral rights in wartime. Russia proposed that "the denomination of a blockaded port is to be given only to one which has the enemy vessels stationed sufficiently near to cause an evident danger to the attempt to enter." Although little came of Catherine's initiative, the government of the United States incorporated this proviso into its Treaty Plan of 1784, and it sought international recognition of this principle.
In the seventeenth and eighteenth centuries, the practices of nations vis-à-vis blockade tended to follow their treaty obligations, and those treaties spelled out a wide variety of reciprocal rights and duties that would become operative in time of war. Naturally, a good many of the arrangements concerned the proper implementation of the rules of blockade, for nations that were neutral had no wish to become embroiled in the quarrels of their neighbors. It might be said that no branch of international relations received more attention than the search for a viable definition of blockade, one that would protect the rights of neutrals without too seriously impeding the war efforts of belligerents. Part of the reason for a certain tolerance on the subject stemmed from necessity: the naval powers of that day, Britain and Holland, depended upon Scandinavian sources of naval stores. Prudence dictated a circumspect policy toward the northern neutrals of Europe, while the conditions of warfare made such a policy easier to pursue.
In that time of limited war, full-scale blockades were rarely imposed, for men-of-war and privateers usually found it more profitable to waylay merchantmen that might be subject to seizure and condemnation in a prize court (with consequent enrichment of the captors). In prize law, problems of blockade violation remained largely a subdivision of the law of contraband until the era of the wars of the French Revolution. In the 1790s, British Admiralty officials began to pay closer attention to the problems posed by blockade. The altered circumstances of the time required new approaches, and all concessions toward neutrals had to be reevaluated.
The struggle that engulfed Europe from 1793 to 1815 ushered in a new era of international relations. Changed conditions of warfare required the belligerents to impose heavy restrictions on trade with the enemy. Almost at once, Great Britain and France narrowed their definitions of neutral rights; and as the struggle between them intensified, both nations demonstrated that they would take whatever measures seemed necessary to defeat the enemy. At one point the French proclaimed that there were no neutrals, and the British echoed that sentiment. According to one commentator, international law, if it existed at all, had been known only "through the declamations of publicists and its violation by governments." Whatever the cynicism of that mot, it accurately reflected the views of an age caught up in revolutionary upheaval.
When the wars of the French Revolution led Britain to an assault on America's presumed right of unfettered trade with all the nations of the world, belligerent as well as neutral, Secretary of State Thomas Jefferson drew up a strong protest. The provision order of 1793 had instructed British naval commanders to bring in for preemptive purchase all neutral ships en route to French ports with cargoes of corn, flour, or meal. By this arbitrary redefinition of contraband, by an order that would keep American grain out of French markets in Europe and in the West Indies, by a decree that arrogantly restricted American produce to the ports of Britain or its allies, the infamous provision order threatened the new nation's honor and interests. The threat led Jefferson to a spirited defense of America's canons of commerce and international law. After denouncing the British order as contrary to the law of nations and asserting that food could never be classified as contraband, he acknowledged a "single restriction" on the right of neutrals to use the seas freely: "that of not furnishing to either party implements merely of war … nor anything whatever to a place blockaded by its enemy." Jefferson thus put his finger on an important point, for if food could be classified as contraband, as an implement of war, British cruisers could legally seize it on American ships. If an order in council could declare entire islands of the West Indies or the entire coast of France blockaded, then Americans could carry nothing whatever to those places.
In the practice of the times, a legal blockade "entitled the blockading power to intercept all commerce with the blockaded port and to confiscate ships and cargoes of whatever description attempting to breach the blockade." As a nation that lived largely by export of foodstuffs, America had a vested interest in the outcome of arguments on the fine points of international law.
But Jefferson could not bring the British around to his view. Nor could John Jay when, in 1794, he went to London to draw up a commercial treaty and to resolve a number of simmering disputes, including claims for damages that had grown out of the British attacks on American commerce. In part, Jay sought to bring the British around to Jefferson's definition of neutral rights, to get them to agree that foodstuffs could never be classified as contraband (although they might be captured on ships attempting to enter a blockaded port). In these negotiations the Americans also desired British assent to the definition of effective blockade incorporated in the Armed Neutrality of 1780. Unable to obtain these arrangements, Jay had to be satisfied with a British promise to indemnify American citizens for captured articles "not generally regarded as contraband," and for assurances that vessels approaching a blockaded port would be turned away rather than captured, if the captain had no knowledge of such blockade. Beyond these innocuous concessions the British refused to go.
Meanwhile, on the French side during the 1790s, matters became so trying for the United States that a quasi-war broke out in 1798, largely because of French interference with American commerce. Lasting two years, the war ended with the Treaty of Mortefontaine (better known as the Convention of 1800), which contained a Napoleonic affirmation of neutral rights, including a narrow definition of blockade. No altruism dictated such a concession; in all probability Napoleon sought to embarrass the British for their provision order and for other executive acts of the British cabinet that both interfered with his supplies and irritated neutrals by their arbitrary nature. Or he may have sought to lure the United States into another league of armed neutrals that was then forming in Europe.
The Treaty of Amiens (1802) momentarily brought peace to Europe, but when war resumed barely a year later, the concept of neutral rights and the definition of blockade again came in for heavy pummeling by both belligerents. Horatio Nelson's victory at Trafalgar in October 1805 and Napoleon's at Austerlitz in December of that year made England supreme on the sea and France supreme on land. As Napoleon moved from triumph to triumph thereafter and consolidated his hegemony over the Continent, the British sought to bring him down with ever more restrictive maritime regulations. The military stalemate required full-scale economic war, which spelled trouble for the neutrals. The British had already tightened up on neutral trade with French colonial possessions by invoking the Rule of 1756—a diktat that forbade in wartime trade not allowed in peacetime—to cut neutrals out of the profitable French carrying trade.
During the wars of Napoleon, blockade proved the most potent weapon in the arsenals of both belligerents, although sometimes its bark was worse than its bite. Upon becoming prime minister in 1806, Charles James Fox sponsored an order in council that declared the coast of Europe, from Brest to the Elbe, in a state of blockade (although its prohibitions were absolute only between the Seine and Ostend). It amounted to a paper blockade, unsupported by ships stationed off the ports in blockade. Even the mistress of the seas did not have sufficient ships to cordon off so extensive a portion of seacoast.
The French responded with the Berlin (1806) and Milan (1807) decrees. These imperial enactments placed the British Isles in a state of blockade, and any ship submitting to search by British cruisers or complying with regulations requiring a stop at a British port the French considered denationalized and a lawful prize. Essentially a set of domestic French regulations, Napoleon's continental system remained legal in territories under French control, in the dominions of its allies, or in consenting neutral countries. The system amounted to "a fantastic blockade in reverse." Its main purpose was not blockade but the ruin of British commerce, as Napoleon himself admitted. "It is by dominating all the coasts of Europe that we shall succeed in bringing Pitt [the Younger, then prime minister] to an honorable peace," he had written in 1800, but "if the seas escape us, there is not a port, not the mouth of a river, that is not within reach of our sword." By denying his adversary access to continental markets, the emperor hoped to destroy British power.
Faced with competing blockades (the British, for their part, desired only to push their own goods onto the Continent, contrary to Napoleon's desire), confronted with ever more restrictive practices on the part of the European belligerents, the neutral United States twisted and turned, without finding a satisfactory resolution of its dilemma. On one occasion President Jefferson told the French minister in Washington that "we have principles from which we shall never depart. Our people have commerce everywhere, and everywhere our neutrality should be respected. On the other hand we do not want war, and all this is very embarrassing." The situation called for action, but action risked war. Under such circumstances, and given the peaceful proclivities of the Jeffersonians, it was tempting to resort to ingenuity; the more so because Napoleon had cunningly remarked in the Milan Decree that its provisions would not be enforced against neutrals who compelled Britain to respect their flag. The president sponsored a series of legislative enactments, including the embargo of 1807–1809, which, through unfortunate timing, coincided with the apogee of Napoleonic power. The baleful effects of the embargo helped convince some Federalists in Boston and elsewhere that the president was in league with the emperor. Nothing could be further from the truth. The European situation remained beyond the influence of American stratagems, no matter how ingenious, as Jefferson and his successor James Madison learned.
The British openly violated their own blockade of Europe by a system of licenses encouraging neutrals to carry both British and colonial goods through the French self-blockade, albeit after those goods had passed through British hands at a profit. In 1807 some 1,600 such licenses were granted; and by 1810 the number had reached 18,000. By that time Russia had deserted the continental system, opening the Baltic to neutral and British trade.
The result of all these twists and turns, taken under the name of blockade, was an extension of the war that soon involved the United States. Unable to control the periphery of his system, in Spain, Portugal, and Russia, Napoleon took his Grande Armée to Moscow and disaster. The object of that campaign, of course, was to force the Russians back into the system and to reconstruct his continental blockade. Shortly before this great effort commenced, the United States, with its sixteen assorted ships of war, entered the conflict against England. Soon the British blockaded ports in the American South and West, although they carefully refrained from blockading New England, where there was much disaffection with Mr. Madison's war. Merchants who carried foodstuffs for British troops received passes through British squadrons. For two months after the declaration of war, the British consul in Boston licensed cargoes.
The wars of 1793–1815 clearly demonstrated the irreconcilable difference between belligerents and neutrals over use of the flexible doctrines of blockade. For the belligerents, especially the naval powers, blockade was a weapon that, if used imaginatively, could do much to bring the enemy to its knees; for the neutrals, blockade constituted a danger to trade and a means of involvement in the war. To the extent that a neutral acquiesced in "unlawful" definitions, that nation decreased its impartiality by actions that gave sustenance to one side while denying it to the other. Conversely, a too vigorous assertion of neutral rights might involve the nation in war. Still, the imprecisions inherent in formulations satisfactory to all, hence to none, provided loopholes that required no great legal legerdemain to stretch meanings to fit the exigencies of a particular war. By selecting from an assortment of precedents and practices, a belligerent could easily define the rules of blockade so as to make neutral commerce a victim of the drive for victory.
When the British sought to close the Continent to neutral trade or to control that trade in their own interest by whatever arbitrary or quasilegal means they might devise, their higher objective, the destruction of Napoleon's warmaking capacity, took precedence over abstract, poorly defined, and largely unrecognized neutral rights and theoretical definitions of how the Royal Navy might or might not use one of its most powerful weapons. In like manner, when Napoleon's continental system came into conflict with American views of proper conduct, the emperor proved no less ingenious or heavy-handed in bending practice to fit his military or economic objectives. Between the infringements of the British and French, Americans had little to choose. Caught between implacable forces in the war that raged over Europe for nearly a generation, Americans struggled to define and defend principles for which the world, at that dangerous time, could find no use. When war threatened the safety of the state, right gave way to might. In its life-or-death struggle for national existence, Britain could not countenance interpretations of blockade that interfered with the pursuit of victory. Failure to understand that fact of international life did much to embroil the United States in a war it did not really want.
A WARLESS ERA
With the close of the Napoleonic wars in 1815, attendant upon Waterloo and the emperor's banishment to St. Helena, there followed almost a century when, with the possible exception of the American Civil War, no major conflict involving neutral rights took place. The important wars of the nineteenth century, from 1815 to 1914, were either civil conflicts such as the Taiping rebellion in China (1850–1864) and the American Civil War, or land wars of relatively short duration such as the Franco-Prussian War (1870–1871). Commentators on the law of war therefore had ample opportunity to refine their concepts and to sharpen their definitions. Statesmen of the time, especially American leaders, stressed the need for a new, more reasonable international order. As secretary of state, Madison had set the lines of this litany when he denied the legality of a British blockade of the entire islands of Martinique and Guadeloupe. In 1805 he told the British chargé d'affaires in Washington that international law required the presence of sufficient force to render "access to the prohibited place manifestly difficult and dangerous." In defense of this doctrine—and for the sake of American exports of food and naval stores—he added: "It can never be admitted that the trade of a neutral nation in articles not contraband, can be legally obstructed to any place, not actually blockaded." In 1824, Secretary of State John Quincy Adams ventured a new definition of a legal blockade, one that required "ships stationary or sufficiently near" the place prohibited, so that there was "evident danger" in attempting an entry. Then, during the Mexican War (1846–1848), the United States again affirmed its opposition to nominal blockades by telling the neutral British that according to American rules, "no Mexican port was considered blockaded unless a force was stationed sufficiently near to make trade with that port dangerous."
The United States refused to adopt the 1856 Declaration of Paris by which the major European powers at the end of the Crimean War attempted to promulgate a new code of neutral rights. That set of rules included a revised definition of blockade: "Blockades, in order to be binding, must be effective—that is to say, maintained by a force sufficient really to prevent access to the coast of the enemy." That article coincided with traditional American views. Other portions of the declaration did not measure up to Washington's expectations of what a proper code of conduct should be. During the war, with the fighting mainly on land and hardly touching neutral commerce, the maritime powers, France and Britain (then allied against Russia), realized that privateers, that is, legalized private ships of war, might prove attractive to the Russians in some future war. Having renounced use of such vessels during the war, the victorious allies sought in peace a formal international prohibition against their use. Part of the price for such an abolition was adoption of a more liberal view of neutral rights, and the powers of Europe, including Britain, subscribed to the rules set out at Paris. Hence, the ideal statement about blockade. But the American government, like the Russian, found fault with the new code. With its small navy, the United States might find future utility in use of private vessels of war and was therefore reluctant to surrender their use. Until belligerents were willing to afford a total immunity to all private property at sea, the Americans did not want to abolish privateering. They sought, rather, to trade off American acceptance of the article abolishing privateers for European recognition of the principle of immunity for private property at sea during wartime.
Failure to sign the Declaration of Paris did not enhance America's status as a champion of expanded neutral rights or as a proponent of the need for clear limits to blockades. Nor was the American position advanced by the circumstances of the Civil War, a conflict that became so heated—the need to contain the rebellious South being so pressing—that Washington officials proved willing to abridge the national record on the rights of neutrals, particularly in the use of blockade theory and practice, if only such abridgment would bring victory. Indeed, some observers and later historians have argued that the United States had been a champion of neutral rights when it had a small navy and little military power, but when it marshaled the most effective army and largest navy in the world, it jettisoned the principles of an earlier generation in favor of a more expedient approach.
In retrospect, the Civil War seems to have been so large an anomaly in American national life that no easy judgment can be made on whether President Abraham Lincoln and his aides forsook the principles of the Founders to save the Union. For the president and his secretary of state, William H. Seward, the fundamental international problem during the war was to preserve the neutrality and if possible the goodwill of Britain. Blockade measures against the South therefore had to be arranged so as to put maximum pressure on the Confederacy without provoking British reprisals. To be sure, other European neutrals occasionally encountered difficulties—Spain, for example, because of ownership of Cuba, from whence blockade-runners sometimes passed, and Denmark because of the proximity of the Virgin Islands to the Confederate coast—but their involvement never reached crisis proportions. The Mexican government frequently complained about actions by Union captains off Matamoros, contrary to the Treaty of Guadalupe Hidalgo (1848), which forbade any blockade of the Rio Grande. But the British response to problems generated by the war always concerned Union leaders most, for they realized that Britain's international position, its merchant fleet and naval strength, gave Her Majesty's government a vital interest in transatlantic affairs. For example, when the British almost from the outset of the war failed to push any blockade cases with the American government, that forbearance provided Lincoln's administration with a helpful leeway in manhandling aid for the South coming in by sea, or any effort by Southerners to ship cotton abroad in order to import the arms and supplies needed to prosecute the war. Britain's lack of militancy on issues concerning blockade became so marked by the second year of the war that the federal government in Washington enjoyed virtual carte blanche in its measures to seal off the South from supplies.
At the outbreak of war the Lincoln administration made a slip, when on 19 April 1861 it proclaimed a blockade of Southern ports from South Carolina to Texas and then eight days later of the ports of North Carolina and Virginia. The president should have declared the ports closed. Proclamation of a blockade was a presumption that the South enjoyed belligerent status and might merit international recognition as an independent nation. Officials in London felt that, in any event, they could not look upon 5 million people as pirates or as engaged in unlawful combination, and on 13 May they issued a neutrality proclamation, which included a warning to British subjects against the violation of any blockade established by either belligerent. Months later, in July, President Lincoln tried to amend the legal faux pas by saying that the blockade was "in pursuance of the law of nations" against a domestic insurrection: "A proclamation was issued for closing the ports of the insurrectionary districts by proceedings in the nature of blockade." These changes in legal terminology did not result in European withdrawal of recognition of Confederate belligerent status.
Later, debate would focus on the effectiveness of the Union blockade or on the "proceedings in the nature of blockade." Writers have contended that Union efforts were effective, but one twentieth-century southern historian argued that the blockade was a sieve. He calculated that blockade-runners made 8,000 trips to the South. He further points out that, in the early stages, the Union did not have sufficient ships to give even a semblance of effectiveness to its declaration. The porous nature of the blockade invited attempts to run into Southern ports with profitable cargo. Many of the adventurers who tried their hand at the business were "retired" British naval officers and other subjects of Her Majesty, the Queen. So many Britons took part in blockade-running that Lord John Russell, the foreign secretary, offhandedly quipped that his countrymen would, "if money were to be made by it, send supplies even to hell at the risk of burning their sails." Throughout the war, profits remained high; a return of 1,000 percent upon investment was not uncommon. Even in 1864, a captain who ordinarily made $150 per month might earn $5,000. A popular toast celebrated the blockade-runners' thankfulness to everyone: "The Confederates that produce the cotton; the Yankees that maintain the blockade and keep up the price of cotton; the Britishers that buy the cotton and pay the high price for it. Here's to all three, and a long continuance of the war, and success to blockade-runners." Still, the blockade was effective enough for the British government, despite considerable pressure against the move, to recognize its existence. Lord Russell, who can hardly be described as pro-North in outlook, eventually concluded that the Union blockade had to be considered "generally effective against foreign trade." His minister in Washington, Lord Lyons, regarded it as more than a mere paper blockade, noting that if it were "as ineffective as Mr. Jefferson Davis says … he would not be so very anxious to get rid of it." From reports of the commander of their North American station, the British carefully monitored the performance of Union blockading squadrons, and not until early 1862 did they formally accept the blockade. In February of that year, Russell told Lyons that there were enough Union vessels on blockade duty to prevent access to Southern ports or "to create an evident danger" to ships seeking to enter them.
Another Southern wartime hope—that the need for cotton would force European powers to press Lincoln's government to relax its blockade— also proved illusory. As it turned out, King Cotton proved a weak champion and an inept diplomat. By chance, the crop of 1860, one of the largest on record, had been shipped to Europe before the war started, and by the time a shortage developed, in the winter of 1862–1863, the South's military position was too precarious to warrant European intervention in American affairs.
One additional facet of the Civil War blockade deserves mention. Four captures of ships made during the first months of the war raised questions about the right of the federal government under international law to establish a blockade of its own ports during an insurrection, and of the right of the president to do so in the absence of a congressional declaration of war. Attorney General Edward Bates was advised to delay the cases until the president could appoint more politically reliable justices to the Supreme Court. After three Lincoln appointees joined the court, the government's position on the utility of the blockade was barely upheld in 1863, by a vote of five to four. The five cooperative justices made up in ardor what they lacked in support from their less certain brethren; and the dissenters no doubt blanched to hear that they had taken the "wrong" side of an issue involving "the greatest civil war known in the history of the human race," and that their negative arguments had threatened to "cripple the arm of the government and paralyze its power by subtle definitions and ingenious sophisms."
In one of the prize cases, that of the Springbok, the court ruled that any cargo ultimately intended for a blockaded port could be captured whenever it left the territorial waters of its port of origin. This rule applied, the court said, "even if the cargo was to be transshipped at an intermediate port, and the vessel in which it was found when captured was not the one which was to carry it to a blockaded port." In this case the court assigned a penalty for a breach of blockade "to a guilty cargo in an innocent ship." The court, in effect, ruled that the cargo was on a continuous voyage from its port of origin to a blockaded port. Acceptance of this definition increased the power of the Union navy in intercepting supplies en route to the South. Such rulings went far toward making a blockade of Confederate ports almost unnecessary by substituting what amounted to a paper blockade of neutral ports in the Caribbean and Mexico. The case of the Peterhoff raised a question of the shipment of contraband overland, from Matamoros, Mexico, across the Rio Grande to Brownsville, Texas. The Union navy found itself with a perplexing problem in Matamoros, which before the war had had scarcely half a dozen visiting vessels a year. This hardly vibrant entrepôt welcomed 200 ships by 1864. Union captains hesitated to move against a neutral port, but they took ships en route to it, the Peterhoff being one of their more famous captures. After the war the case of the Peterhoff came before the Supreme Court; Chief Justice Salmon P. Chase roundly affirmed America's traditional record of respecting neutral ports and internationalized rivers such as the Rio Grande; he also asserted that the nation did not favor paper blockades. Release of the ship seemed a reasonable price for so many reassuring affirmations.
In another ploy to increase the efficacy of the blockade, Union officials even refused clearances to suspicious cargoes from their own ports or required the posting of heavy bonds to assure that such cargoes were intended for peaceful purposes. (During the war, suspiciously large amounts of clean-burning anthracite coal, a key component of successful blockade-running, were being shipped to British ports in Canada and the Caribbean.) The British chargé d'affaires complained about these export restrictions, remarking that the congressional enactment that sanctioned them was "a cheap and easy substitute for an effectual blockade." These practices so irritated British merchants that in 1864 Lord Lyons threatened that Her Majesty's government might have to reconsider its recognition of the legality of the Union blockade. Secretary of State Seward knew that, so late in the war, such an action could not serve British interests, so he ignored the minister's protest. For the remainder of the war the Union continued to use all the legal and economic weapons that it possessed to defeat the South.
During the half-century from the close of the Civil War to the opening of World War I, there were only one or two refinements in the concept of blockade. As noted, the Franco-Prussian War provided no opportunities for the expansion of old definitions or the creation of new ones. The Boer War and the Spanish-American War were local conflicts—the one a civil war, the other a splendid little affair. In the course of operations before Manila, prior to the capture of that city in 1898, Admiral George Dewey came to dislike the pretensions of a German admiral who happened to be in the harbor, and there is some evidence that Dewey told his German opposite that he wanted to "damn the Dutch." But that was hardly a refinement of blockade; nor did anything of a novel nature accompany use of blockades in the Caribbean, although the closing off of Santiago de Cuba was one of the last pre-submarine, close-in blockades, while the one at Havana, which began on 22 April 1898, had a closer connection with strategic considerations than with economic ones. The Americans believed that they could not capture Havana Harbor without risking heavy losses.
More important developments took place in a contretemps before the ports of Venezuela in 1902, when Britain, Germany, and Italy instituted a blockade to collect the debts owed by Venezuela to European creditors. The United States served notice that there was no right to interfere with ships of third parties, that is, American ships; whereupon the blockading powers announced that their blockade "created ipso facto a state of war" and gave themselves belligerent rights. When the issue went to the Permanent Court of Arbitration, the tribunal carefully skirted questions about the legality of the blockade, but in adjudicating the claims of the creditors decided in favor of the blockading powers. Shortly thereafter the nations of the world made another illustrious, if inconsequential, pronouncement about blockade. The second Hague Peace Conference (1907) had sought to establish an International Prize Court, but the delegates could not agree on the rules of prize law. To fill this gap a conference met in December 1908 in London, and after two months the delegates signed the London Declaration. Its provisions on blockade demonstrated once again the great difficulty in arriving at a satisfactory definition; indeed, these men of the twentieth century did little better than their nineteenth-century counterparts at Paris in 1856. Unable to agree upon a definition that would be acceptable to all, and recognizing the need for a "certain imprecision," the delegates reaffirmed the illegality of paper blockades and said that for a blockade to be binding it had to be maintained by an "adequate" naval force. No government ratified the London Declaration, even though during World War I the United States pressed the British to accept its principles. The resultant refusal highlighted a basic ambiguity of international life. Despite the best intentions, a power at war will retain loopholes in commitments to other nations so as to permit maximum use of offensive and defensive weapons.
WORLD WAR I AND AFTER
The theory and practice of blockade entered a third stage (following the formative period in the seventeenth and eighteenth centuries and the somnolent period dating from 1815) when the major nations of Europe joined in the Great War in 1914 and the United States entered the conflict in 1917. In the opening campaign along the Marne, the French army and a small British force slowed the German army, and the war turned from movement to position. By this time, the narrow definitions of the Paris and London declarations were all but obsolete—inoperable except in the most unimportant situations. Those formulations could not serve the needs of twentieth-century war. Transportation networks had grown up across all modern countries—rivers and canals, railroads, macadamized roads and highways for motor travel. New navies of steel and steam plied the seas, epitomized by the launching of the British battleship Dreadnought in 1906, and the conversion of merchant shipping from sail to steam was virtually complete. The new network of transportation made enemy ports of less consequence as goods could be shipped in and out via nearby neutrals. The conversion to steam made it unnecessary for warships to catch the wind before they moved out against blockade-runners or illicit neutral traders. Merchant shipping could operate apart from trade routes and prevailing winds, quite literally turning up anywhere. Then, too, the industrialization of much of Western Europe, especially of Germany, the principal antagonist of the Allies, gave a new dimension to blockade— the right sort of blockade might destroy German industry, or at least severely cripple it. And, as if blockade in the sense of Grotius and Bynkershoek would have had much chance at all, practical submarines and highly reliable mines were invented just prior to the outbreak of the war. Small wonder that World War I virtually ended blockade as it had been known.
In several instances, the old, traditional blockade of close-in surveillance of enemy ports was practiced during World War I, but these operations, carried out in reasonable conformity to the strictures of the London Declaration, occurred in secondary theaters of naval activity—the Mediterranean, Africa, and China. Where things really mattered—the blockade off the European coast and in the North Sea—the British government at least made a formal effort to maintain that the old rules still roughly applied. Its foreign secretary, Sir Edward Grey, indulged in frequent long explanations to the American ambassador in London and to the secretary of state in Washington. He assured them and reassured them that any changes in traditional rules of blockade stemmed not from a spirit of innovation but from the need to adjust old definitions to new circumstances. He implied that nothing really had changed.
In fact, the purposes of a blockade during the war were assisted by other measures not given that name, and the belligerents were usually careful in avoiding use of that term to describe their actions. The outstanding examples of such measures were the German declarations of war zones and the British designations of mine areas, military areas, and danger zones. It was a piquantly interesting fact that every one of the belligerent resorts to what might be described as measures of quasi-blockade was adopted via the principle of international law known as the law of retaliation.
It is hardly necessary to explain in detail how the British and German blockades operated during World War I. The Germans first used mines, giving notice of their intent to do so in August 1914; the British countered in November by closing the entire North Sea because of minefields. In a proclamation of 4 February 1915, the Germans announced unrestricted submarine and mine warfare, and the following month the British and French retaliated by declaring their intent to detain and take into port all ships "carrying goods of presumed enemy destination, ownership, or origin." To the Americans, Grey described that move as a blockade, and the U.S. government took his note as a formal notice of the establishment of a blockade and sought to get the Allies to respect neutral ports and vessels according to traditional standards of international law. In responding to the strictures of Washington officials, Grey took the stand that the March order amounted to "no more than an adaptation of the old principles of blockade." A decade later in his memoirs he wrote more candidly: "The Navy acted and the Foreign Office had to find the argument to support the action; it was anxious work."
And well done. The order in council of 11 March 1915 was one of the most powerful weapons in the British system of economic warfare against Germany. With the order the Allies gained all the advantages that would have come from a formal declaration of blockade of German ports—and without the inconvenience of stationing "adequate" naval forces off the ports. Also, when the Royal Navy acted under that mandate it succeeded in reducing the flow of supplies to the enemy via neutral ports, while at the same time cutting down on Germany's overseas trade. If the Allied pursuit of victory impinged too closely upon the interests of neutrals, if American shippers complained about innovations or illegalities, the lawyers at the Foreign Office had little trouble finding arguments.
Ironically, the British government found quite a few in the practices of the Union navy during the Civil War. One of the more interesting adjuncts to the British system of blockade closely paralleled a technique used by the North in its efforts to subdue the South, although there is no evidence that the British borrowed the idea from the Americans. From 1861 to 1865, Union officials sought to cut off supplies to the Confederacy by requiring exporters to obtain licenses, which, of course, could only be procured upon evidence that the cargoes in question had a bona fide neutral use. During World War I the British played a variation of this theme in order to make their restrictions more acceptable to neutrals. Their system, called navicerting, worked thusly: A neutral exporter, say an American interested in perfectly legal, noncontraband trade with a Scandinavian country, applied to British authorities (usually a consul) for permission to send his ship through naval cordons guarding approaches to European coasts. If he convinced the consul of the innocence of his venture, he received a navicert, a sort of commercial passport, which in most cases assured noninterference with his ship and cargo. The innovation conferred enormous advantage on the British, for in effect it transferred control of a large measure of neutral trade "from the deck to the dock."
The Allies introduced other refinements in their practice of blockade. They censored neutral mail to discover firms trading with the enemy and then blacklisted them and subjected them to harassment, such as depriving them of coal or denying them facilities for repairs. In the case of the Kim a British prize-court judge accepted statistical evidence to establish a presumption that American goods consigned to a Danish port were actually on a continuous voyage to Germany. Prize courts also made a slight but significant alteration in procedure when they transferred the burden of proving the innocence of a cargo to the claimant. With such pressures the British secured neutral cooperation with their system of economic control. The alternative, to be sure, was not to cooperate, but the Allied supremacy at sea meant that noncooperation had unpleasant consequences: detention of cargo, expensive and time-consuming legal proceedings, confiscation of goods, and the denial of facilities needed to conduct business. All the while the German blockade of Britain moved back and forth from observance of rules of cruiser warfare (meaning that submarines would not sink on sight but instead would visit and search and if necessary make provision for the safety of passengers and crew) to the waging of unrestricted submarine warfare, with its barbaric killing of noncombatants.
With a poor harvest in the United States in 1916 it appeared possible to prevent grain from other neutrals entering the British Isles, and in that hope the German government at the end of January 1917 announced unrestricted submarine warfare and knowingly brought the United States into the war, believing that their submarine blockade would bring victory before the Americans could raise and transport an army to Europe.
That the Allied long-range blockade of Germany was effective in helping the Allies win the war must admit of little doubt. Its effect upon the enemy, however, took far longer than expected. During the great German offensives in the spring and early summer of 1918, the troops were astonished at the quality of the equipment of the routed British Fifth Army, and also at the relative luxury in which French civilians were living. In the last weeks of the war the German home front virtually caved in. The military forces had been defeated first—there may be no doubt about that. But the civilians had been standing in line for years, and the word Ersatz had become a commonplace. When the prospect of peace emerged during the diplomatic exchanges of October 1918, the German civilians came to believe that they had suffered too long. The British blockade at last had placed an impossible burden. Continuation of the war into 1919, which otherwise might have been possible, was too harrowing to contemplate.
In examining the operation of the blockade during World War I, there remains the practice of the United States once it entered the war. Popular wisdom at the time and later had it that the Americans turned the principles of neutral rights around as soon as they became a belligerent. Such was not the case. There appear to have been only two clear-cut and rather minor violations of international law by the U.S. government. Use of embargoes, bunker control, and the blacklist were all unquestionably legal, involving only domestic jurisdiction and municipal law. The task of enforcing the blockade remained in British hands; the U.S. Navy took no prizes. It is true that it laid a great barrier of 70,000 mines from Scotland to Norway. During the period of neutrality, the United States had reserved its rights on British and German mining of the seas, and so, technically at least, did nothing startlingly novel by constructing a huge mine barrier in 1918. Fear of German use of Norwegian territorial waters disappeared when Norway closed the gap in the barrage by mining its own waters. In the pre-armistice negotiations with the British about their insistence upon reserving freedom of the seas from discussion at the peace conference (because they feared it might restrict the right of blockade) President Woodrow Wilson stated that blockade was "one of the many things which will require immediate redefinition in view of the many new circumstances of warfare developed by this war." But there was, he said, "no danger of its being abolished."
In the decades to come, "blockade" as a term would give way to terms such as "quarantine," "interdiction," and "interception." The belief was that the new world organizations, the League of Nations and, later, the United Nations—not to mention the Kellogg-Briand Pact (1928), by which almost all the nations of the world renounced and outlawed war—ensured that neutrality in the old sense was gone, perhaps replaced by collective security.
The record of the League of Nations in this regard was probably too short to be conclusive. Article 16 of the Covenant of the League of Nations provided for sanctions, and the first assembly of that organization created an International Blockade Committee, which issued a cautious report in 1921. The committee felt that "to pronounce an opinion in regard to the naval blockade and the right of search" was outside the scope of its work because more study was needed on those subjects. It noted that three great exporting countries (the Soviet Union, United States, and Germany) remained outside the league, and in a curious bit of logic concluded that its name was a misnomer, since application of Article 16 did not involve imposition of blockades in the traditional sense.
In the 1930s there was talk, in and out of the league, about quarantining aggressors. Membership in the league did not seem to make much difference in the results of the talk, for there were virtually no results. League members hesitated to include an oil embargo among the measures invoked against Mussolini's adventure in Ethiopia in 1935–1936, for the Duce said that he would consider an oil embargo an act of war. In 1937, President Franklin D. Roosevelt spoke in Chicago about quarantining aggressors, but he gingerly withdrew the idea when it aroused a storm of protest from his fellow citizens. In that troubled decade before the outbreak of World War II, there was plain evidence that neutral thoughts had not disappeared. In 1932 the United States ratified a Pan-American Convention that reaffirmed the belligerent right of visit and search. The neutrality acts (1935–1941), passed by Congress to keep the country out of war, went into great detail about neutral rights and duties, including those that involved blockades. The acts implied that for the United States the league's new order would not function. Nor did it.
During World War II the United States again was forced to confront the problems of blockade, both as a neutral and as a belligerent. While neutral, it took an indulgent stand in regard to British blockade measures and sought to avoid repetition of the arguments during World War I. The United States reserved its rights under international law but in practice reached a cozy accommodation with British restrictions, including a much expanded version of the navicert system. Then, as a belligerent, the United States found frequent occasion to expand the use of blockade as a weapon of victory. When the U.S. Navy achieved dominance in the Pacific, it instituted a tight cordon around the Japanese home islands to cut off imports and enforced that cordon with the chilling efficiency of its submarine fleet. Clearly, the demands of total war imposed a need for permutations of what international lawyers describe as the latent law of blockade—the belligerent that possesses command of the sea is entitled to deprive an opponent of use of it. Drafters of the Dutch Placaart of 1630 would have understood that need.
But what had been appropriate to the period of total war proved inappropriate to the era of limited wars that plagued the world after 1945. Once more the United States devised modifications in its use of blockade. These variations have been called "special function blockades" and had a wide use in the Korean and Vietnam wars, during the Cuban missile crisis of 1962, and in conflicts with unfriendly regimes in Iraq, Haiti, and the former Yugoslavia in the 1990s.
Because of its predominant naval power during the Korean conflict, the United States imposed a close-in blockade of all Korean ports and coasts that was reminiscent of the practice of earlier eras. In Vietnam, other tactics were used to interdict the flow of supplies to enemy contingents operating in South Vietnam. To prevent introduction of war matériel by sea, the South Vietnamese, with the aid of U.S. naval craft, conducted what might be described as a self-blockade. During this time they practiced all the traditional techniques of visit and search off their own coasts and in their own territorial waters. Perhaps a more interesting case was the mining of Haiphong Harbor and the internal waterways and coastal waters of North Vietnam by American aircraft in the spring of 1972. By this process of air interdiction of seaborne supplies the United States hoped to carry out the purposes of a blockade, and took extreme care to minimize the danger to neutral commerce. The U.S. Navy even observed the ancient custom of allowing a grace period for neutral vessels to leave the coast and harbors before activating the mines.
The most important invocation of a special function blockade occurred in the Caribbean during the missile crisis in October 1962. Thus, the United States relied on one of the oldest weapons in its arsenal to avoid resorting to more deadly ones. In a speech to the nation, President John F. Kennedy announced "a strict quarantine of all offensive military equipment under shipment to Cuba" and a turning back of all ships found to be carrying offensive weapons "from whatever nation or port." The subsequent proclamation ordered U.S. forces to interdict delivery of such matériel, and the navy set up a quarantine line around the eastern and southern approaches to the island. The president carefully coordinated his naval maneuvers so as to leave room for compliance by the Russians with these restrictions on their freedom of the seas. Successful resolution of the missile crisis again demonstrated the protean possibilities of concepts of blockade or "proceedings in the nature of a blockade," that is, as flexible instruments of national policy.
In the case of blockading—such in reality was the word behind the other words—of Iraq that began in August 1990, the action against Iraqi trade divided into phases I and II. Phase I came at the outset of Operation Desert Shield, the effort by the United States together with a large number of other members of the United Nations to persuade Iraq to give up its occupation of Kuwait, which it had just accomplished. The lead in this effort to make Iraq move its military forces back behind its own borders was necessarily taken by President George H. W. Bush, for it was mostly U.S. Navy forces that would have to handle restrictions on ocean-borne trade; 95 percent of Iraq's exports were oil. The president skirted mention to blockade, at first referring to interdiction, then to interception. His effort to avoid a possible act of war was due to the sensibilities of UN members, some of which—notably France and Russia—were not in favor of strong measures. The president also hesitated because of lack of full support by Congress. But diplomacy abroad and at home gradually resolved the fears of the president's critics. Only two pipelines exited Iraq, one to Turkey and the other to Saudi Arabia. The former nation was cooperative, as was the latter, with a border to Kuwait. The only local supporter of the Iraqi dictator, Saddam Hussein, was Jordan, the monarch of which, King Hussein, might have been expected to oppose Iraq, where Saddam's political party, the Baath, had murdered Hussein's cousin, King Faisal, years before. Jordan's trade with Iraq also was at stake. President Bush managed to persuade Hussein to support a naval interception. As the months passed, with U.S. forces and those of its allies gathering in preparation for Operation Desert Storm, Saddam managed to alienate even more UN members by defying, if only in words, the interception of tankers by the U.S. Navy. To no avail the Iraqi representative in the UN denounced what he described as a U.S.-dominated action, asserting it was naught but a blockade. Phase II of interception of Iraqi trade commenced after the triumphant few weeks of Desert Storm, and, to the confusion of U.S. and UN officials, continued into the twenty-first century. The basic problem during Phase II was to get the Iraqi regime to change its ways, for they were intolerable—a total disregard for human rights, support of international terrorism, hegemonic ambitions in the area, and development of weapons of mass destruction and missile delivery systems, not to mention refusal of reparations for its invasion of Kuwait. But how to force a reformation? Claims by Iraq that children suffered from lack of food were difficult to resist, and the UN was tempted to allow oil for food if only to pay Kuwait and nations such as Jordan, which had to house and feed refugees during Desert Shield and Desert Storm, as well as nations whose nationals had been trapped in Iraq during that time. Meanwhile, the U.S. Navy's interceptions were difficult to enforce. Ships bringing cargoes into the country, particularly container ships, had to make space for inspectors, and the loss of cargo thereby led to complaints. Ships destined for Jordan's port of Aqaba required inspection at sea or at the port prior to land transshipment. Sentiment arose, encouraged by Iraq, to hold inspections at a designated point on the Jordan-Iraq border, so that the Iraqis could boast about doing everything properly, while goods could come in at other border points illegally and without notice. (The borders in the area had no passes or notable roads; they were lines drawn in the sand after World War I.) In 1997 the commander of the U.S. Fifth Fleet accused Iran of complicity for smuggling oil through Iranian territorial waters. As late as March 2001 a notable breach in the interception was occurring by land transit of oil into Turkey, with the oil duly taxed by the Turkish government. Both the United States and United Nations informally accepted the traffic, amounting annually to hundreds of millions of dollars, for it benefited the weak Turkish economy.
Meanwhile, between 1991 and 1994 actions leading to interdiction were taken in Haiti, to force out a military regime that had deposed an elected president, and against Serbia for attacking Slovenia and Croatia, which had declared independence from Serbia. At the beginning in Haiti the international opposition was marshaled by the Organization of American States and was voluntary. At last, in 1993, the United Nations took over from the OAS and imposed mandatory prohibition on entry of oil, arms, police equipment, and "spare parts for the aforementioned." There nonetheless was trouble over border smuggling from the Dominican Republic, the government of which reluctantly allowed policing by U.S. military helicopters. On 19 September 1994, without any clear evidence that a limited embargo had had any effect, a small invasion force landed and the military regime came to an end.
In regard to Serbia, a situation developed not unlike that of the American Civil War, in which the Yugoslav federal government, dominated by Serbia, sought to bring back its independence-minded provinces. Two international squadrons stationed in the Adriatic undertook to enforce an embargo. But the government in Belgrade needed no arms support, unlike its seceding provinces. And other supplies to Serbia were easily available via the Danube or neighboring states. As in Haiti, naval measures of interception ultimately failed, and led to employment of air power and land-based peacekeeping forces.
And so the meaning of "blockade" has shifted over the years—perhaps it is more correct to say that it has been "jostled." Everything has depended upon the nation with available power, whether that nation wished to employ it for its own benefit or that of the international community. At the time when international law was a novelty, the time of Grotius, there was no such thing as an international community. In the seventeenth, eighteenth, and nineteenth centuries, blockade was a point of argument governed by power and, for the United States, by hope—trust that trading nations could make their ways without interference. After World War I the word "blockade" tended to go out of style. The international organizations created after the world wars anticipated the prevention of conflicts through the cordoning off of "aggressor" nations by multilateral action and not by the traditional bilateral maneuvers involving blockade. Then, too, other words—"quarantine," "interdiction," "interception"—have seemed less provocative than "blockade" and also would not automatically involve inconvenient rules and practices of the not-too-distant past.
As to the future of blockade, it may not have one. New words from the late twentieth century give indication that it is a concept of the past.
Behrens, C. B. A. Merchant Shipping and the Demands of War. London, 1955.
Bernath, Stuart. Squall Across the Atlantic: American Civil War Prize Cases. Berkeley and Los Angeles, Calif., 1970. Makes international law not only intelligible but interesting to the general reader.
Deak, Francis, ed. Neutrality in History, Economics, and Law. 4 vols. New York, 1935–1936. Treatment of the evolution of a key portion of international law.
Field, James. America and the Mediterranean World: 1776–1882. Princeton, N.J., 1969.
Gilbert, Felix. To the Farewell Address: Ideas of Early American Foreign Policy. Princeton, N.J., 1961.
Lurabaghi, Raimonndo. A History of the Confederate Navy. Annapolis, Md., 1996. Translated by Paolo Coletta.
Mallison, W. T. Studies in the Law of Naval Warfare: Submarines in General and Limited Wars. Washington, D.C., 1968. Legal problems raised by submarine war.
Medlicott, W. N. The Economic Blockade. 2 vols. London, 1952.
Moore, John B. Digest of International Law. 8 vols. Washington, D.C., 1906. Old but useful.
Savage, Carlton. Policy of the United States Toward Maritime Commerce in War. 2 vols. Washington, D.C., 1934. Handy compilation of documentary material.
Savelle, Max. The Origins of American Diplomacy: The International History of Anglo-America, 1492–1763. New York, 1967. Although there is no index entry for blockade, there is the important chapter "The Impact of the New World of the Colonies upon the Evolution of the Theory and Practice of International Law."
Siney, Marion C. The Allied Blockade of Germany: 1914–1916. Ann Arbor, Mich., 1957.
Tracy, Nicholas. Attack on Maritime Trade. Toronto, 1991. The perspective is from naval strategy rather than economics or international law.
Trask, David. Captains and Cabinets: Anglo-American Naval Relations, 1917–1918. Columbia, Mo., 1972.
Varg, Paul. Foreign Policies of the Founding Fathers. East Lansing, Mich., 1963.
Wise, Stephen. Lifeline of the Confederacy: Blockade Running During the Civil War. Columbia, n S.C., 1988.
See also Armed Neutralities; Arms Transfers and Trade; Continental System; Economic Policy and Theory; Embargoes and Sanctions; Freedom of the Seas; International Law; Naval Diplomacy; Neutrality .
KENNEDY AND THE CUBAN MISSILE CRISIS
"Good evening, my fellow citizens. The government, as promised, has maintained the closest surveillance of the Soviet military buildup on the island of Cuba. Within the past week unmistakable evidence has established the fact that a series of offensive missile sites is now in preparation on that imprisoned island. The purpose of these bases can be none other than to provide a nuclear strike capability against the Western Hemisphere….
"Acting, therefore, in the defense of our own security and of the entire Western Hemisphere, and under the authority entrusted to me by the Constitution as endorsed by the resolution of the Congress, I have directed that the following initial steps be taken immediately: First: To halt this offensive buildup, a strict quarantine on all offensive military equipment under shipment to Cuba is being initiated. All ships of any kind bound for Cuba from whatever nation or port will, if found to contain cargoes of offensive weapons, be turned back. This quarantine will be extended, if needed, to other types of cargo and carriers."
—From a radio and television address by President John F. Kennedy, 22 October 1962—
"Now, therefore, I, John F. Kennedy, president of the United States of America, acting under and in virtue of the authority conferred upon me by the Constitution and statutes of the United States, in accordance with the aforementioned resolutions of the United States Congress and of the Organ of Consultation of the American Republics, and to defend the security of the United States, do hereby proclaim that the forces under my command are ordered, beginning at 2:00 Greenwich time October 24, 1962, to interdict, subject to the instructions herein contained, the delivery of offensive weapons and associated material to Cuba.
"For the purposes of this Proclamation the following are declared to be offensive material: Surface-to-surface missiles, bomber aircraft, bombs, air-to-surface rockets and guided missiles, warheads for any of the above weapons, mechanical or electronic equipment to support or operate the above items, and any other classes of material hereafter designated by the Secretary of Defense for the purpose of effectuating this Proclamation."
—Proclamation signed by President Kennedy, 23 October 1962—
By the time of the French and Indian War (1754–63), the blockade had become one of Britain's major instruments of war. But when the American Revolutionary War began (1775), the Royal Navy was too weak to blockade distant colonial ports. The entry of France and Spain into the war worsened the British position. In 1781, a brief blockade of Chesapeake Bay by a French fleet played an important role in bringing about the surrender of a British army at the Battle of Yorktown, and as a result, the end of the war.
After an arduous campaign in the southern states, Gen. Charles Cornwallis moved his army to Yorktown, Virginia, on the Chesapeake, where the British fleet could resupply and reinforce it easily or, if necessary, evacuate it entirely. As the colonial and French armies under George Washington and count de Rochambeau marched south from New York and Newport to strengthen the small force besieging Cornwallis, ships bearing the French artillery and supplies sailed in convoy from Newport toward the same destination. The British fleet under Adm. Thomas Graves departed New York in order to intercept the French ships as they approached the Chesapeake. The French ships Graves found, however, were those of Adm. count de Grasse's fighting fleet recently arrived from the Caribbean. They had Cornwallis under blockade. In a long but not very bloody fight, de Grasse repulsed Graves and sent him back to New York. The convoy from Newport arrived safely, the allied armies besieged Cornwallis closely, and de Grasse forestalled any British attempt to rescue the trapped army. His situation hopeless, Cornwallis surrendered. The war petered out, and the colonies gained their collective independence. By itself de Grasse's blockade would not have led to that result, but in combination with the effective work of the allied armies, it served perfectly.
The next American experience with blockade, during the War of 1812, was grim. By this time the British Fleet had long regained its strength and more, and it had had nearly twenty years of experience in blockading enemy ports in the wars of the French Revolution and Napoleon. Most of the famous American frigate victories in this war took place in the early months, before the British could deploy forces sufficient to lock the ships of the small U.S. Navy into whatever port they happened to be. As the blockade grew tighter and extended further, American foreign trade dried up. So did American domestic trade, most of which went by water. Farmers could not sell their crops; merchants lost their businesses, employees their jobs. Moreover, without tariffs on imports, the government had little money. In addition, the U.S. invasion of Canada had failed; British warships sailed the Chesapeake; and British troops had burned Washington. Despite American successes on Lakes Erie and Champlain, and spectacular raids by American privateers upon British shipping, the American people were ready for peace. So were the British, who had been at war almost without a break since 1793. In December 1814, the opponents signed a treaty of peace.
Soon after the outbreak of the Civil War President Abraham Lincoln, knowing that the Southern states manufactured little, ordered the U.S. Navy to blockade the Southern ports so as to prevent them from importing arms and other goods from Europe. This the navy attempted, first by using armed commercial steamers and then by adding new ships built for the task. The blockaders drove sailing ships, mostly neutral, out of the trade with the South. But those ships were replaced by swift steamers, again mostly neutral, which sailed from Bermuda and the Bahamas mainly toward Charleston, South Carolina, and Wilmington, North Carolina. By war's end in 1865, the blockaders had driven ashore, sunk, or captured three‐quarters of the 300 blockade‐running steamers. But the latter kept the Southern armies supplied with arms until early in 1865, when Northern forces took Charleston from inland and seized the sea approaches to Wilmington. That spring, Gen. Robert E. Lee surrendered, but not for lack of arms. It is easy to quantify the effort expended on the blockade, but difficult to judge its contribution to the North's eventual success.
Early in the twentieth century, developments in naval mines, torpedo craft, and coast artillery made it plain to the Royal Navy that close blockade was no longer possible. Hence, when World War I broke out in 1914, the Grand Fleet took station at Scapa Flow, north of Scotland, whence, in conjunction with forces in the Channel, it kept the German High Seas Fleet locked uselessly in the North Sea. Protected by the Grand Fleet, old warships and armed merchant cruisers as well as minefields effectively carried out a commercial blockade against both belligerent and neutral merchant ships trying to enter not only Germany's ports but also those of its neighbors.
The Germans responded with a counterblockade against shipping attempting entry into or exit from Allied ports, especially those of Britain. Their instrument was the submarine, a small warship that could sail surprising distances, could hide under the water when attacking or in danger, and that carried the most deadly of naval weapons: torpedoes and mines. By the spring of 1917, when—partly as a result of the brutality of the submarine campaign—the United States joined in the war against Germany, that campaign was driving Britain, the last strong combatant among the Allies, to defeat. The Allied decision to convoy merchant ships rather than to let them continue sailing singly, combined with the arrival of enough U.S. destroyers to make convoy possible, defeated the submarines. The sailing of 2 million American troops to France made possible by this success gave the Allies the edge in strength to halt and then reverse the German offensives in 1918, and that in turn led directly to the end of the war.
The Allies were more vulnerable to blockade than the Germans, but although the submarines were beaten, the Allied blockaders kept their stranglehold on Germany's economy months after the war had ended.
By its nature the submarine, unable to rescue its victims, brought a new savagery to a hitherto not very bloody form of war. Aircraft, soon to join in the war at sea, suffered from the same shortcoming and the savagery worsened.
So far as blockade and counterblockade went, World War II in the Atlantic and Mediterranean followed the pattern of the preceding war. The chief difference was that both sides were better prepared than before to resist the other's blockade. In the Mediterranean and the narrow seas of Europe, aircraft took a leading part in the conduct of blockade. In the Pacific War, the Japanese made no particular effort either to attack enemy shipping or to protect their own. In contrast, the Americans, led by their submarines, destroyed Japanese shipping. This meant that the empire's troops often perished when being moved to where they were needed. For lack of fuel, Japan's pilots could not be trained adequately, and toward the end, its fighting ships could not sail. The blockade was the primary contributor to the defeat of Japan.
In more recent conflicts, blockades have again played significant roles. But in the long struggle against North Vietnam (1965–73), because of an implied (or inferred) threat of Soviet retaliation, the United States imposed no blockade on North Vietnam during the first seven years U.S. combat forces were engaged in that war. As a result, three‐quarters of the arms, ammunition, and fuel that the North used in the Vietnam War entered by sea in ships from the Soviet Union. Finally, in 1972, the United States mined the approaches to North Vietnam's harbors, and the traffic stopped. This, combined with hard fighting on the ground and in the air that used up the North's arms stocks, particularly its surface‐to‐air missiles, led to a peace agreement between that country and the United States that permitted the withdrawal of U.S. forces. These events illustrate both the value of blockade under the conditions of that war and the ease by which an interested and more clever government was able to forestall for years the imposition of a blockade on the Soviet Union's client state.
In itself, blockade is not often likely to achieve much. Used wisely and unremittingly against a foe dependent on sea traffic, however, and in tandem with vigorous action elsewhere, it can be a highly effective instrument of war.
[See also Submarine Warfare.]
Sir Julian S. Corbett , Some Principles of Maritime Strategy, 1911; repr. 1972.
S. W. Roskill , White Ensign: The British Navy at War, 1939–1945, 1960.
G. J. Marcus , The Age of Nelson: The Royal Navy, 1793–1815, 1971.
Clay Blair , Silent Victory: The U.S. Submarine War Against Japan, 1976.
Paul M. Kennedy , The Rise and Fall of British Naval Mastery, 1976.
Stephen R. Wise , Lifeline of the Confederacy: Blockade Running During the Civil War, 1988.
John B. Hattendorf, ed., Mahan on Naval Strategy: Selections from the Writings of Rear Admiral Alfred Thayer Mahan, 1991.
Frank Uhlig, Jr. , How Navies Fight: The U.S. Navy and Its Allies, 1993.
Paul G. Halpern , A Naval History of World War I, 1994.
Frank Uhlig, Jr.
Blockades were a specific kind of warfare in which one country attempted to reduce its opponent's economic ability to wage war by cutting its ports off from seagoing trade with other nations. Historically, nations at war have used either close blockades or long-range blockades to stifle their enemy's trade. In close blockades, ships were stationed within miles of the enemy's port, forming an impregnable ring through which no trading ship could pass unseen. If that kind of blockade was impractical, however, the blockading ships could be positioned far off of the coast, or along the entire coastline—safe from enemy interference but still close enough to stop blockade-running vessels.
Over time international laws and treaties were developed to govern the use of blockades. For example under the Declaration of London of 1909, any neutral country that traded with the enemy of a blockading country had to be officially notified in advance that its ships would be stopped if they tried to run the blockade. Similarly, blockades had to be applied equally to the vessels of all countries, and blockades could only be established at ports occupied by the blockading country's enemy—a neutral country's port could not be blockaded.
Because seagoing trade with other countries had always played a major role in the U.S. economy, blockades had been a common feature of its history. During the War of 1812 (1812–1814) the United States was the victim of a very effective British blockade that almost totally stifled U.S. trade with neutral countries. During the American Civil War (1861–1865), the North implemented an effective if costly blockade of 3,500 miles along the Confederate coast. By the war's end the blockade had closed off every Southern port except for the one at Galveston, Texas.
The invention of submarines, airplanes, and missiles made it virtually impossible for any nation to maintain a traditional close blockade of an enemy's port. In the twentieth century, blockades took a more informal form, such as Germany's loose submarine blockade of Great Britain in World War I (1914–1918). The blockade became particularly important to the United States when a German submarine sank the passenger ship Lusitania in 1915. One hundred and twenty-eight U.S. citizens were killed, and the United States moved a significant step closer to entering the war against Germany. Later on, President John Kennedy (1961–63) initiated a successful blockade of Cuba. During the height of the Cold War in 1962, he ordered the U.S. Navy to prevent Soviet ships from delivering to Cuba nuclear missiles that were to be pointed at U.S. cities.
BLOCKADE, the closing by sea of the coasts and ports of an enemy in such a manner as to cut off entirely the enemy's maritime communications. Naval blockades have played a prominent role in U.S. diplomacy since the Revolutionary era. At that time, the United States had a small navy and a large merchant marine and therefore sought to limit the scope and uses of blockades. In 1784 the Continental Congress argued that a blockade was legitimate only if a nation closely patrolled an enemy's coast and ports. During the Napoleonic wars, however, Britain and France went far beyond this definition in order to cripple each other. In May 1806 Britain declared a blockade around the entire European coast, from the Elbe River to the port of Brest, although the British had far too few ships to patrol such a vast area. Napoleon responded by closing all European ports under his control to British shipping and to neutral vessels that had either traded at a British port or been searched by British cruisers. The United States protested that these declarations went far beyond the traditional practice of blockade. In his 1812 war message to Congress, President James Madison named Britain's "mock blockade" as one of the chief grievances of the United States against the British.
Ultimately, the American limited definition of blockades prevailed. The Declaration of Paris (1856) stipulated that a blockade was binding only if the nation involved maintained "a force sufficient really to prevent access to the coast of the enemy." Ironically, the United States did not sign the declaration, because it objected to another provision in the agreement outlawing privateers, and large-scale blockades became central to American military strategy. At the onset of the Civil War, President Abraham Lincoln proclaimed a blockade of the Confederate coast, which proved vital to the Union's victory. After the Civil War the United States became a naval power and moved away from its limited definition of blockades. American forces, for example, often relied on the expansive doctrine of "continuous voyage," which held that a nation could seize foreign ships destined for neutral countries if it could prove that their cargo would eventually reach a blockaded port.
By the time of World War I the development of submarines, mines, and long-range artillery made traditional "close" blockades almost impossible. During the war Britain rejected the Declaration of Paris and used minefields and cruiser patrols to establish a "far" blockade around Germany. Although the United States protested this action, German naval strategy soon outraged Americans even more. In 1915 the Germans exacerbated tensions with the United States when they announced a policy of unrestricted submarine warfare in the waters surrounding Great Britain. This "blockade," which many Americans construed as a flagrant violation of traditional warfare, eventually brought the United States into the war on the side of the Allies. In World War II, submarines and aircraft again altered the nature of blockades. During the conflict the United States and Britain employed a long-range air and naval blockade against Germany, while the Germans used unrestricted submarine warfare against the Allies. Blockades also shaped the course of the Cold War. In 1962 the United States imposed a "quarantine" of Cuba to stop the Soviet Union from shipping offensive weapons to Cuba and to force the Soviets to dismantle missiles already on the island.
Bess, H. David, and Martin T. Farris. U.S. Maritime Policy. West-port, Conn.: Greenwood Press, 1981.
Hickey, Donald R. The War of 1812. Urbana: University of Illinois Press, 1995.
LaFeber, Walter. The American Age. New York: Norton, 1994.
Spivak, Burton. Jefferson's English Crisis, 1803–1809. Charlottesville: University Press of Virginia, 1979.
block·ade / bläˈkād/ • n. an act of sealing off a place to prevent goods or people from entering or leaving: the army has imposed an economic blockade. ∎ anything that prevents access or progress: the police pulled down blockades on the highway.• v. [tr.] seal off (a place) to prevent goods or people from entering or leaving.DERIVATIVES: blockader n.