Sea power

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sea power. The strategy of sea power in the Second World War remained in essence what it has been since man first took to the water, began trading, and succumbed to a state of war: deny the seas to the other side while retaining control yourself. In the Napoleonic wars, French armies could range across Europe and east as far as Moscow, but the UK's coastline and commerce were usually safe so long as the kingdom could dominate the seas. Admiral Mahan referred succinctly to ‘those far distant, storm-beaten ships, upon which the Grand Army never looked’, which ‘stood between it and the dominion of the world’. With the ultimate defeat of the combined fleets of France and Spain at the battle of Trafalgar, on 21 October 1805, the Royal Navy ensured the security of the nation from invasion and its trade from interference. The control of the seas by the UK remained virtually unrivalled for a hundred years. By 1914, however, the challenge by the German and Austro-Hungarian Central Powers had become highly intimidating. Neither of these empires possessed any naval tradition but the massive German fleet was imbued with professionalism and possessed first-rate material.

The ships and weapons of all navies in 1914 were infinitely more sophisticated than at Trafalgar. The guns mounted on battleships, themselves capable of 24 knots, could fire accurately at an opponent almost beyond the horizon, while submarines could fire their torpedoes unseen to a lethal distance of over 9,000 metres (9,840 yards). Tethered mines, which had paid a crucial part in the most recent naval war, between Russia and Japan in 1904–5, added a new offensive and defensive dimension to weaponry. Aeroplanes and airships ranged the sky on reconnaissance, ‘spotted’ for the guns and searched the seas for German submarines (U-boats).

Before the First World War ended in an Allied victory, brought about substantially by the failure of the German Navy to break the blockade which was starving the Central Powers of food and war materials, the submarine had proved to be the most dangerous fighting ship, while the bomber and torpedo-carrying plane posed a threat to the future of old naval weaponry. Yet nothing had altered the strategic principle of sea power.

To replace Germany as a challenger to British naval dominance there emerged from the First World War two new naval powers, already in competition with one another. The naval tonnage figures sum up the situation in 1922. Japan 547,000; the USA 1,100,000; the UK 1,400,000. Nineteen years later, Japan had torn up all the international treaties of limitation in numbers and size of warships designed to prevent a repeat of the ‘battleship race’ between Germany and the UK in the years between 1900 and 1914. Its naval tonnage had doubled to 1,100,000 while the USA had added only some 250,000 tons to its strength in 1922.

This Imperial Japanese Navy (IJN), scarcely half a century old, had been brought into being by British-built ships, and inherited British traditions and officer training. Before and during the First World War, and between the wars, Japan had built up a large and first-rate shipbuilding industry, and by 1941 Japanese weaponry and the naval air arm were the equal of any other navy. The great weakness was the lack of an industrial base in any way competitive with that of the USA.

The US Navy began to rearm and modernize in the mid-1930s as Japan demonstrated aggressive and truculent attitudes, invading China (see China incident) and building illegal bases in the Marshall Islands. Simultaneously, the British Royal Navy laid down new tonnage, reacquired control of its neglected air arm from the RAF, and introduced radar and less inadequate protection against bombing, as Hitler marched into neighbouring nations such as Austria and Czechoslovakia.

At the same time, Germany began the construction of a modern fleet, previously prohibited under the terms of the Versailles settlement following the First World War. The new navy, designed this time for the guerre de course rather than direct confrontational battle, was not due to be ready before 1941–2, but with Hitler's limited faith and interest in sea warfare, that was no deterrent to the opening of his land and air campaigns in September 1939.

German strategy at sea was to attack Allied shipping wherever it could be found with surface raiders (see auxiliary cruisers and German surface raiders) and U-boats. During the last weeks of peace, a number of fast, modern, and heavily armed warships, with their supply ships, were dispatched to the North and South Atlantic, and even into the Indian Ocean, to await the order to open hostilities. At the same time, almost the entire U-boat fleet of some 40 vessels put to sea and took up station in the North Sea and the Atlantic approaches to British and French western ports.

For the UK and her allies and Commonwealth, the tasks were closely similar to those in 1914. Again, the U-boats became an instant menace and the surface raiders hard to find and difficult to destroy. By contrast with the days of sail, the raider now had the advantage of speed, radio communications and even radar, and (in some cases) a spotter seaplane to extend the area of search for prey. But the modern raider also suffered from the need to refuel and avoid damage far from repair facilities; under sail a raider had been largely self-supporting.

There were numerous occasions when the threat of gunfire caused a raider to sheer off at speed. An early British success in damaging the German pocket battleship Admiral Graf Spee (see River Plate), leading to her self-destruction, acted as a salutary lesson and signal for even greater caution among raider commanders. In all, the cost to the Germans of surface raiding was too high for the toll exacted.

There were abundant lessons to be learned on the Allied side, too. It should not have been necessary as the two most important lessons had been acted upon before, and somehow forgotten. In 1917 the maritime war—and therefore the war itself—had been almost lost by the Allies as a result of the failure to introduce convoys to protect merchant ships, a defensive precaution known and practised in the days of sail.

Fortunately, for the Allies, this mistake was not repeated; the complex machinery for introducing convoys had been set up again in the UK in 1937, and the first convoy sailed within a few days of the beginning of the war at sea. But convoying was of a strictly limited nature, in part because of the shortage of suitable escort craft, a handicap which prevailed for many months.

Churchill, as First Lord of the Admiralty in 1914–15, had called for an offensive strategy towards the U-boats, with hunting groups ranging the oceans. The chances of finding one, conveniently on the surface, proved highly unlikely. When he came back to the Admiralty in 1939, with his same urge to take the offensive, hunting groups, in some cases including precious and vulnerable aircraft carriers, were again formed, to negligible effect. Only when one large carrier had been torpedoed and sunk and a second brought close to destruction, was Churchill's folly ended, albeit slowly and by stages. ‘It is only politicians who imagine that ships are not earning their keep unless they are rushing madly about the ocean,’ remarked the British First Sea Lord, Admiral Pound, sardonically.

Churchill cannot, however, be held to blame for the loss of the treaty bases in Eire, by their voluntary surrender to Dublin in 1938, contrary to treaty obligations. These had proved of inestimable value for the protection of the Western Approaches in the First World War, and now their loss was to cost the lives of many thousands of merchant seamen in the battle of the Atlantic.

Another renewed threat facing merchantmen and warships alike on both sides was mine warfare. The sea mine was now a more sophisticated weapon than that one which had restricted the movements of the fleets in the North Sea in 1914–18, and rebuffed the British and French navies in the Dardanelles in 1915. The Germans had perfected a magnetic mine, which could be laid by aircraft or fast small warships in coastal shipping lanes and entrances to harbours. It claimed many victims in the first winter of war before an answer was found to it.

As in 1914, German mercantile trade was reduced to a trickle by the instant Allied naval blockade (see also economic warfare) which sealed off the northern entrance to the North Sea with cruiser patrols, and RAF Coastal Command air patrols, and effectively prohibited passage of the Dover Straits to U-boats and merchantmen by minefields and light patrol boats. Contraband cargoes destined for Germany in neutral vessels were seized from the first days of war.

At the start of the battle for the Mediterranean, Italy's navy posed a threat even while at first abstaining from any hostile activity. The British Navy made itself responsible for the eastern basin based on Alexandria, while the French covered the sea west of Malta. The French and Italian navies were comparable in strength, both possessing a few modern heavy ships and numerous fast cruisers and destroyers, backed up by surviving First World War tonnage. air power could be exercised by Italy from land bases.

Substantially, this was the strategic scene in the opening months of hostilities. The similarity with 1914 was almost uncanny. The best survivors of the middle-rank officers of the earlier war were now in senior command, the wiser for their earlier experience. The battleship was still considered effectively the final arbiter of sea power, and more of these behemoths were fitting out or on the stocks of many naval shipyards; while air power was, amazingly, still seen only in terms of reconnaissance, spotting for the big guns, perhaps damaging further a retreating opponent, locating surface raiders, and providing cover for convoys.

The British Home Fleet was again worried about the security of its northern base at Scapa Flow, with reason. The submarine was, once again, surprising both the Germans and the British by its effectiveness. The Royal Navy again efficiently transported the small British Expeditionary Force to France, without losing a man. Plus ça change plus c'est la même chose indeed!

Churchill's ‘Gallipoli’ of 1940 was the attempt to close off the Swedish iron ore trade (see alsoraw and synthetic materials) with Germany down the Norwegian coast by occupying Narvik (see Norwegian campaign). But once again political delays and procrastination nipped a brilliant strategic concept in the bud: the Germans got there first. In failing to intercept effectively the German invasion of April– May 1940, the British and French navies suffered a severe setback, which shocked the American president and people.

The Allied navies' successful withdrawal of troops from Narvik and Trondheim, and on a vastly larger scale, the British and French troops blocked in at Dunkirk, offset the lamentable performance in Norway, even though the German Navy suffered crippling losses there.

With the fall of France in June 1940, and entry of Italy into the war on Germany's side, the fate of the powerful French Navy became a serious preoccupation. Many of the French warships were neutralized, or turned over to the British Navy. But other heavy units had to be attacked, unsuccessfully as it turned out at Dakar, successfully at Oran in North Africa (see Mers-el-Kébir). Although the loss of lives was regrettable and embittered the French people, the UK's evident determination to pursue the war even without allies greatly impressed the US public.

Alone now in the summer of 1940, the British and Commonwealth navies were fully stretched keeping open the trade routes to North and South America, South Africa, Australasia and the Far East, and through the Mediterranean for the supply of men and materials to the land campaigns and the vital oil of the Middle East. It was an even more complex and critical strategic problem than that posed in the Napoleonic campaigns against the navies of France and Spain at the turn of the 18th–19th centuries.

The Italians suffered major defeats on land in the Western Desert campaigns and Mussolini's assault on neutral Greece, which began the Balkan campaign, was blessed with no better fortune. Meanwhile, Hitler, acquisitive eyes for long set on the east, determined to clear up these failing campaigns before invading the USSR (see BARBAROSSA). The effect of this intervention was felt immediately.

The British Navy was deeply and expensively involved in the unsuccessful attempts to hold back the German tide in Greece, and then in Crete. Much criticism was levelled at what was seen as strategical folly. In fact, it may have delayed BARBAROSSA by 3–4 weeks, and the onset of the Russian winter almost certainly saved Moscow and Leningrad, and the USSR itself. Only sea power could have brought this about. The UK could also claim the moral kudos of meeting its commitment to support Greece, again important to American opinion.

As the war progressed, the USA, while remaining nominally neutral until December 1941, was offering more and more material aid to the UK under Lend-Lease, especially in aircraft and naval vessels, and co-operating with the Canadian Navy in guarding the western end of the Atlantic convoys.

From the outset of the German–Soviet war, Churchill pledged the fullest possible support in war materials of all kinds to the Soviet war effort. This put yet more strain on British naval resources. Everything had to be shipped in the Arctic convoys to northern Soviet ports, or later via the southern route through Persia.

It was at this time that the loss of Norway was most seriously felt. Although the UK had built up bases in Iceland, the Arctic convoys, which carried aircraft, tanks, and all manner of military matériel for the hard-pressed Red Army, were vulnerable to shore-based German bomber and torpedo-carrying aircraft, U-boats and surface ships—including the new mighty battleship Tirpitz, which lurked among the northern mists in its well-concealed anchorage.

These Arctic convoys, stoutly supported with the aid of the US Navy after Germany declared war on the USA on 11 December 1941, cost many ships and many thousands of lives. To the displeasure of Stalin, they had to be halted from time to time, but the material they delivered proved vital to the survival of the USSR.

Meanwhile, the battle of the Atlantic continued with increased relentlessness, and new tactics and weaponry. Code breaking took an important part in the defeat of the U-boat packs (seeULTRA, 1), but it was the escort carrier with its short-range aircraft, and the advent of very long range heavy bombers and flying boats, which turned the tide. By May 1943, when convoys were first able to sail the entire Atlantic under land-based air cover (see air gap), German losses reached unacceptable heights, and U-boats were forced away to distant waters for their prey.

A further skill the sailor had to learn and perfect if the war was to be won by the Allies was that of amphibious warfare. Commando raids on occupied France took place within days of the fall of France. These early amphibious operations, calling for the closest co-operation between the army, the navy, and sometimes the air force, were not notably successful. But knowledge was constantly being built up for the large-scale landings which followed. These required a new strategy on a radical and giant scale, as well as new skills in bombarding defences and bringing men and supplies to land on hostile coasts at minimum cost in lives. The first requisite of successful amphibious warfare was control of the sea, which, in turn, presupposed control of the air.

By the time the men and shipping had been assembled in southern England for the Normandy invasion in June 1944 (see OVERLORD), the techniques and art of amphibious warfare had been thoroughly exercised in the Pacific. The peacetime US Navy of 1941 was a fine service suffering from limited resources but enjoying presidential approval and encouragement. The attempt by an army air force lobby, led by Colonel Billy Mitchell, to prove the superiority of army air power, had a double-edged consequence, resulting as it did in the setting up, in 1921, of a bureau of aeronautics within the navy department which led to the formation of both a navy and a marine corps air arm.

The lack of American bases in the Pacific also led, faute de mieux, to fleet self-subsistence and long-range capability. The US Pacific Fleet in the years leading to war with Japan had not only evolved the carrier task force but also the Fleet Train, including tankers (oilers), transports, repair ships, ammunition and cargo ships. Efficient landing craft were used in amphibious exercises, and integration between all classes of warships was refined through the 1930s.

All manoeuvres were conducted on the premise that Japan would be the opponent, and as late as 1938 a surprise ‘attack’ by carrier-borne aircraft on Pearl Harbor in the Hawaiian Islands was conducted as an exercise—with complete success, it should be noted. The material strength of the Japanese Navy was understood, but the quality of the personnel and weaponry was underestimated.

With the real attack on Pearl Harbor in December 1941—‘This is no drill! This is no drill!’—and the simultaneous attacks on American, British, French, and Dutch bases and territory in South-East Asia, the Philippines, and the South Pacific, initial Allied strategy was perforce one of confinement and defence. The vulnerability of the battleship—demonstrated earlier by the British who had put out of action the Italian battle fleet at Taranto with a handful of obsolescent dive-bombers and torpedo-bombers—was evidenced not only at Pearl Harbor. The British attempt to deter the Japanese from attacking Singapore and Malaysia by sending, without air cover, a modern battleship and older battle-cruiser, ended in disaster (see Prince of Wales and Repulse).

While the big gun was to prove valuable for bombardment use, and the battleship made an excellent platform for multiple anti-aircraft guns to protect the carrier, it was the carrier itself that at once replaced the battleship as queen of the fleet. For some five months after Pearl Harbor, the Japanese carriers swept the Pacific and Indian oceans almost with impunity, mounting raids from Darwin, Australia, to Colombo, Ceylon (see Indian Ocean raid), and on numerous Pacific islands.

The intention of the Japanese High Command was to cripple US naval power, while brushing aside Dutch and British intervention, and so demoralize the American people that a negotiated settlement could be demanded. There was no intention of occupying any part of the US mainland: that would not be necessary in the judgement of Tokyo.

But no greater misjudgement of a nation's character in the face of threat had ever been made. The folly of temporarily wrecking the American battle fleet in a sneak attack only inflamed the determination for revenge. The rate of Japanese successes, which had at first been breathtaking, inevitably slowed. In May 1942, as the industrial might of the American nation geared itself to the production of armaments, and a flood of young men trained for the armed forces, Japanese carrier pilots met serious opposition for the first time when, in the Coral Sea battle, the IJN lost its first carrier. This engagement, in which the US Navy also lost a carrier, heralded an entirely novel form of naval warfare, as it was conducted, for the first time ever, without the ships of the opposing sides ever sighting one another. And the heavy gun, with its maximum range of around 25,000 m. (27,340 yd.), had been superseded by the bombing/torpedo aircraft with a range limited only by the capacity of the fuel tank, and the wind.

Wind had been a consideration in the days of coal-firing and pre-smokeless shell-propellant; and the laying of an artificial smokescreen was an additional wind-dependent factor. Now, in this new carrier warfare, the wind reverted to almost the same importance as it had had in the days of sail. For carriers, these floating airfields, were required to turn into the wind both to launch and to recover their machines, a time-consuming process. Wind strength and direction was also the paramount factor in judging the safe range of a carrier's aircraft, and this calculation was further complicated by the carrier's present and future speed, and course.

During the Pacific war, carrier warfare was usually conducted with the opposing ships beyond visual range of each other. This involved accurate reconnaissance and meteorological intelligence, top-level communications, radio interception and code-breaking, support teams, air-sea rescue vessels to cover airmen forced to ‘splash’, and split-second decision-making among the commanders. (The best American carrier fleet commander, Admiral Spruance, was nicknamed ‘Electric Brain’.) Naval radar, unknown to the Japanese at this time, had been handed over to the Americans by the British. Above all, and as always, successful carrier warfare demanded good luck and individual courage.

American success in early carrier battles such as Coral Sea and Midway contained the Japanese amphibious advance in the central and south-west Pacific, and put heart into the US Navy and Marine Corps just when they were threatened with demoralization. But for many months the situation remained delicately poised. In this new naval warfare the carrier was far more vulnerable than the heavily armoured battleship had been. After Pearl Harbor, the US Pacific Fleet did not lose a single battleship, but at one time it was reduced to a single operational (and damaged) carrier in the South Pacific. Three years later, there were almost 100 carriers operating with the US Navy, the shipyards achieving a launch rate of one per week. How could the Japanese hope to match that?

For the IJN, it was a very different and sorry story. Short of everything but zeal, by a superhuman effort it managed to assemble five fleet carriers and four smaller carriers for the Philippine Sea battle in June 1944, but this equalled the strength of only a single US task force. Of equally ominous significance for the IJN were its relatively inferior aircrew resources. The Japanese aircrews of Pearl Harbor and Midway had been unequalled in skill and experience. But when, inevitably, most of these were lost, their replacements were of steadily declining skills, while the US Navy's aircraft became as good and then better than Japanese ones.

In the island-hopping amphibious Pacific campaigns, the greatest integrated combined operations in history until OVERLORD, it is impossible to weigh the relative contributions of any arm. The land-based heavy bombers of the US Army Air Forces took a larger and larger part as the war advanced and bases within flying range of mainland Japan could be constructed. Then there were the marine corps and army infantry who waded ashore or were landed by air on island after island.

It is also impossible to overstate the importance of the contribution of the US Navy's submarine service, which for propaganda reasons was played down at the time, while German U-boat warfare was being condemned for its ruthlessness. But the submarine campaign against Japanese shipping was quite as unrestricted, and even more effective, hastening the end for the Japanese Empire (see Japan, 7).

Well before the first atomic bomb was dropped on Japan its merchant service had ceased to exist, confirming the imminent total collapse of the empire. Two-thirds of its total tonnage, and two-thirds of Japanese warships, had been sent to the bottom by American submarines. But as Admiral S. E. Morison has written in his official history of this magnificent record (see below), ‘few stories of the exploits were given out and no correspondent was taken to sea before 1945.’

Casualties among the US submarine crews were severe—though not on the scale of German U-boat losses—but no great naval war in history was won with so few casualties as in the Pacific war. By employing in the later stages an almost excessive superiority in matériel and men to attack Japanese-held islands, casualties were kept to a minimum. The principle was sustained that there should be no limit to expenditure of matériel if it resulted in saving a single American life.

In these last months, the IJN virtually ceased to exist, and was reduced to mounting kamikaze suicide attacks. So powerful were the gun and fighter defences of the Allied ships, they generally had a nuisance value only (but see Okinawa).

The overall strategic concept of the war at sea against the powerful and wholly dedicated Japanese, and the conduct of operations, at first against intimidating odds, are difficult to criticize. While it was almost entirely American in contribution and inspiration, and a remarkable example of the rapid response and resilience of the American people and industry, effective British, Australian, and New Zealand participation was welcomed and recognized, perhaps less by the US Navy's C-in-C, King, than by his subordinate commanders serving at sea. Relations remained cordial during all active operations.

The scale of the Pacific naval war, which was without precedent in history, would have exhausted the resources of any nation except the USA. But, with the early decision to make the defeat of Germany the first Allied priority, the US Navy was committed to a two-ocean war. From the North African campaign landings of 8 November 1942, and the subsequent landings in Sicily, Italy, and the south of France (see Sicilian and Italian campaigns, and French Riviera landings) the US Navy operated in the Mediterranean on a large scale and in the same capacity as in the Pacific. But as in the Atlantic, the British contribution was very much larger.

As far as the grindingly drawn-out battle of the Atlantic, and the Arctic convoys, were concerned, US participation was variable according to priorities elsewhere. But the Canadian contribution (see Canada, 6(c)) was steady and consistent, and of greater value than has sometimes been credited to that Dominion.

Two late events, long after Taranto, Pearl Harbor, and the sinking of the Prince of Wales and Repulse, can be seen as marking again the changed nature of warfare at sea in 1939–45. The first was the sinking of the ‘unsinkable’ modern Japanese giant battleship Musashi by carrier-borne torpedo- and dive-bombers, and of the equally formidable German battleship Tirpitz in a Norwegian fiord by British heavy bombers. Neither of these monsters, which had demanded such vast resources and manpower in their construction, had taken any useful part in the war except as vague threats.

By contrast, combined operations, when correctly planned and given surprise and control of the air and the sea, invariably succeeded. Churchill, who had unjustly received the blame for the disaster of the failed combined operations at Gallipoli in 1915, had wished to entitle his First World War history, ‘The Great Amphibian’. It would have been more suitable for his history of the Second World War.

From the day France fell and mainland Europe was at the mercy of Hitler; equally, from ‘the day of infamy’, Pearl Harbor, victory over Germany and Japan could be achieved only by amphibious, or combined, operations, which in turn depended for success on command of the seas. This was as evident in the ferocious struggle for Guadalcanal in the south-west Pacific as at Anzio in Italy and the beaches of Normandy. Even Stalin, like Napoleon essentially a soldier, was forced to recognize this truth, and from the early weeks of the German attack in 1941 applied political pressure relentlessly on the Allies to make a seaborne landing in the west—a Second Front.

The strategy of sea power, and of its first cousin amphibious operations, had not fundamentally altered since Medina Sidonia's Great Armada had failed to defeat Queen Elizabeth I's navy, the Dutch sailed up the Medway, and Napoleon's troops were obliged to sit it out on the Boulogne cliffs. As Captain Stephen Roskill (see below), has written, ‘When we review amphibious warfare in a modern context, here is a case of a historic principle whose validity, at least over a matter of four hundred years, remains quite unchanged’.

Richard Hough

Bibliography

Hough, R. , The Longest Battle: The War at Sea (London, 1986).
Kemp, P. K. , Victory at Sea 1939–45 (London, 1957).
Macintyre, D. , The Battle for the Mediterranean (London, 1964).
—— The Battle for the Pacific (London, 1966).
—— The Naval War Against Hitler (London, 1971).
Morison, S. E. , History of United States Naval Operations in World War II, 15, vols. (Boston, 1948–64).
Roskill, S. W. , The Strategy of Sea Power (London, 1952).
—— The War at Sea, 3 vols. (London, 1954–61).
Ruge, F. , Sea Warfare: A German Concept (London, 1957).

sea power enables a state to use the oceans for commerce and war, while denying these facilities to enemies or rivals and controlling neutral shipping. This has been true since early periods. Sea-battles such as Salamis (480 bc) and Mycale (479 bc) played a part in compelling the Persian king Xerxes to abandon his invasion of Greece. During the struggle between Carthage and Rome for control of the western Mediterranean, fleet engagements at Mylae (260 bc), Cape Ecnomus (256 bc), and the Aegates Islands (241 bc) were equally decisive. The defeat of Marcus Antonius at the naval battle of Actium (31 bc) established the Julio-Claudian imperial dynasty of Rome. Two invasions of Japan launched by the Chinese Mongol emperor Kublai Khan in 1274 and 1281 were disastrous failures because of terrible losses inflicted on their fleets by storms. In 1571, the Christian victory at Lepanto crippled Ottoman naval power in the eastern Mediterranean and delivered a decisive check to Muslim western expansion. Successive Spanish armadas against the protestant English and Dutch, including major efforts in 1588 and 1639, failed because the attackers were unable to win command of the sea. Three hard-fought naval wars between Britain and the Dutch, in 1652–4, 1665–7, and 1672–4, were caused by commercial competition and rival claims to sea power. The victories of the British and Dutch fleets, now in alliance, at Barfleur and La Hogue in 1692 safeguarded the Glorious Revolution of 1688 against a Stuart restoration backed by France. The 18th cent. saw a series of wars in which sea power was crucial, in a world in which sea-borne commerce and overseas empires had expanded markedly. The French Revolutionary and Napoleonic wars (1793–1815) saw the culmination of naval warfare in the age of the sailing warship. Nelson's victory at the Nile in 1798 established British control of the Mediterranean, and Trafalgar on 21 October 1805 set the seal on British naval superiority. During the 19th cent., Britain's naval predominance sustained her world-wide commercial and imperial power, despite revolutions in warship design, including steam propulsion and protective armour.

The late 19th cent. saw increased scholarly analysis of the nature of sea power. Foremost was the American naval officer A. T. Mahan. He sought to explain Britain's success in attaining maritime hegemony, stressing that command of the sea in war could only be attained by the destruction or neutralizing of the enemy fleet. His first book, The Influence of Sea Power in History, 1660–1783 (1890), was particularly influential.

By 1914, while the heavily armed and armoured battleship was still seen as the principal naval weapon, the introduction of torpedoes and submarines had already necessitated protective screens for major warships. In the 1914–18 conflict allied sea power facilitated the dismemberment of Germany's overseas empire and enforced a blockade of Germany and Austria-Hungary. In both the First and Second World Wars, Germany's unrestricted submarine warfare at times seemed potentially decisive. Britain's dependence on overseas trade made her particularly vulnerable, though the introduction of the convoy system reduced losses and the allied navies eventually triumphed.

During the Second World War, advances in naval aviation introduced a further element into the struggle for naval supremacy. The Italian battle fleet, at anchor in its Taranto base, was badly damaged by a tiny force of obsolescent Fleet Air Arm aircraft in a raid in November 1940. In December 1941, planes from a Japanese carrier force crippled the American Pacific battle fleet at anchor at Pearl Harbor, though fortunately the American aircraft carriers were away at sea. Japanese sea power was vital in the allied defeats in the Far East in early 1942, but the survival of the American carriers brought a major Japanese defeat in the battle of Midway in June 1942. The principal Japanese striking force suffered disastrous losses in an engagement in which the main warships involved never saw each other, strikes by carrier aircraft proving decisive. Sea power was important in the European theatre of war, in the battle of the Atlantic, and in the north African campaigns, but its most convincing demonstration was in the allied advance in the Pacific between 1942 and 1945. ‘Island-hopping’ campaigns, moving ever closer to the Japanese home islands, were made possible by the development of forces capable of keeping the sea for long periods, backed by a sea-borne supply system. Before the atomic bomb brought Japan to surrender, her defeat had been ensured by the success of American submarines and aircraft in decimating Japanese shipping, depriving the Japanese war machine of oil and other vital raw materials. Since the 1960s, the submarine armed with nuclear missiles has become the single most potent embodiment of sea power.

Norman McCord

sea power a country's naval strength, especially as a weapon of war.

Sea Power. See Mahan, Alfred T.; Strategy: Naval Warfare Strategy.