BLOCKADE

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.