The Blockade of Toulon, 1810-14: Pellew’s Action, 5 November 1813, Thomas Luny, 1830, National Maritime Museum.
Battle of Port Royal: Harper’s Weekly, November 30, 1861 »
Isolation by a warring nation of a particular enemy area. The employment of naval blockades in war has been practiced since the beginning of recorded maritime history. The first known instances of a blockade took place during the Greek Peloponnesian War in the fifth century b.c. Warships patrolled the coastline of an enemy in order to trap an opposing fleet within its harbors and disrupt maritime commerce. Blockaders might hope that this would force the enemy fleet out to fight.
The maritime nations of Europe were aware of this ancient strategy, but it did not assume critical importance until the eighteenth century. Great Britain was the first naval power to implement a systematic blockade where squadrons of ships were devoted to a permanent blockade of an enemy’s coasts. In the Seven Years’ War (1756–1763), the Royal Navy sealed major French ports by sailing within visual range of French territory. This strategy became known as a close blockade and had the same objectives as that employed by the ancient Greeks. It bottled up the French fleet in its ports, with the chance that it might come out to fight, and it caused economic dislocation through the seizure of ships trying to sail through the blockade to trade with France. Captains who captured these vessels were usually entitled to keep them and their cargoes for prize money. The effects of the first systematic blockade in history were a clear indication of the operation’s worth. By bottling up the French fleet, the blockade cut off needed reinforcements and supplies for the French forces fighting in Canada. The blockade also damaged France’s economy through the loss of maritime trade.
The British employed the blockade a second time in the American Revolution (1775–1783). This operation was also a close blockade, where British forces sealed off the entrances to the major colonial ports. Unlike the blockade during the Seven Years’ War, its goal was not bottling up a battle fleet, as that of the colonies was nonexistent. The purpose was to cut off colonial maritime commerce and prevent the coastal transport of supplies in order to cripple American armed forces. This blockade forced the Americans to rely only on overland transport for supply, disrupted colonial trade, and caused some measure of hardship to the civilian population, which in turn hurt morale.
As the empires and trade of the western European powers expanded, so did their dependence on goods from overseas. This growing need made the military and economic goals of blockade equally important. The critical nature of both of these aspects of blockade was made evident in the French Revolutionary and Napoléonic Wars (1792–1815). When the British entered the war, the Royal Navy employed a close blockade of the important French ports to bottle up the French fleet. Many of the war’s major naval engagements resulted from French fleets trying to break through the blockade. British victories in these and other battles gave the British supremacy of the sea and consequently removed any threat of invasion against Britain.
The economic dislocation caused by the blockade also contributed to the defeat of France. Napoléon spread the effects of the blockade from France to other European states when he forced them to adhere to his Continental System, which was a trade embargo against Britain that began in 1806. The economic hardship caused by this system led to Russia’s withdrawal from the system in December 1810 and a vow from Napoléon to punish Tsar Alexander I. This culminated in Napoléon’s disastrous 1812 campaign into Russia.
The growing economic importance of blockades was also evident in the War of 1812. Here the British mounted another close blockade, with the same strategic goals as in Europe. It bottled up the U.S. Navy’s ships and caused great economic distress. By 1814 U.S. merchant trade was but 17 percent of its prewar 1811 level.
The economic strategic effects of blockades in this age were particularly devastating because there were no internationally accepted rules that governed the scope of operations. Maritime laws in the eighteenth and early nineteenth centuries were the product of commerce agreements between individual nations and did not represent a unified body of opinion. Attempts to create a more uniform code for laws that governed the use of blockades failed. An example is the 1780 League of Armed Neutrality comprising Russia, Denmark, and Sweden. Maritime powers such as Britain and France opposed this course, which led Catherine the Great of Russia to call the attempt the “Armed Nullity.”
Action taken during the 1854–1856 Crimean War resulted in the beginning of changes in this state of affairs. The British and French naval blockade of Russia damaged the maritime trade of the United States, which by this time was a force in world power politics. The Americans championed the principle of freedom of the seas, meaning the ability to conduct trade with any country in peace or war without interference. In 1854 the British tried to placate the United States by surrendering some rights in wartime, particularly the right to capture enemy property in neutral ships. This action led to the 1856 Declaration of Paris, the first attempt to place limits on blockades through the use of international law.
This legislation did little to alter any aspect of blockades in the years immediately following its adoption. The U.S. Civil War (1861–1865) was the first test of the new maritime laws. On 19 April 1861, President Abraham Lincoln proclaimed a naval blockade of the entire Confederate coast. It was a close blockade and its methods violated all the stipulations of the Declaration of Paris. The United States, however, had not signed the Declaration of Paris, as it prohibited the use of privateers. The Americans had relied on privateers in time of war because of their small number of purpose-built warships. As in past blockades, this Civil War operation proved crushing to the enemy and was one of the most effective weapons in the Union arsenal.
The Union violation of the Declaration of Paris did not result in a new conference to discuss further laws to restrict the strategic goals of blockades. The importance of the Civil War blockade lay in technological innovation that foreshadowed future changes. In the Civil War the first successful submarine, the CSS H. L. Hunley, which sank a Union blockader in February 1864, was deployed. In the future, technological advances would challenge the use of close blockades in wartime.
In the meantime, blockade strategy remained largely the same as it had been in the eighteenth century, ignoring to varying degrees the Declaration of Paris. The Russo-Japanese War (1904–1905), however, was the catalyst for additions to international law. Both belligerents engaged in war on the other’s trade, which included the Japanese blockade of Port Arthur and Russian blockades of Chinese ports supplying the Japanese. But the Russian operation proved the more onerous to neutral commerce. Great Britain, whose trade had been most affected, became a champion for the protection of neutral rights in wartime and called for new conferences on the subject. The 1907 Second Hague Peace Conference did little to change existing legislation, but the 1909 Declaration of London altered completely the employment of blockades and undermined the strategic goals of blockades. Future belligerents could only capture enemy merchant ships, an aim inadequate to justify the operation. If a state’s merchant fleet was seized, it could simply redirect its trade through neutral nations.
The British, despite being the principal advocate of the declaration, increasingly doubted the use of blockades in the years that followed. Not only did the new legislation render an effective blockade impossible, but the traditional strategy of its deployment was no longer viable because of technological advances. By the twentieth century, the modern submarine had appeared, armed with the torpedo. In addition, other technological advances, such as improved coastal artillery and mines, diminished the possibility of a successful close blockade. A blockaded power that possessed these weapons could easily inflict great damage on a battle fleet lying just off its shores.
The growth of international law and technological change produced new blockade strategies in World War I (1914–1918). The British blockade of Germany took both of these factors into account, although the British increasingly ignored international law because of the need for greater effectiveness. They initially set up a system whereby ships would be stopped, searched, and, if necessary, sent into one of many ports for examination of their cargoes. The force that performed this task was no longer a close blockade, but a distant one deployed at the passages through which neutral commerce had to pass to reach its destination.
Lacking superiority at sea, the Germans used the new technology of the submarine and torpedo to introduce yet another blockade strategy. On 1 February 1915, the Germans declared a war zone around the British Isles; any ship that entered it would be subject to attack without warning. This strategy did produce significant results for the Germans, but in the end it proved disastrous to their war effort. Both blockades contravened international law, but the German blockade led to the loss of neutral lives. When Germany resumed unrestricted submarine warfare, the United States responded by declaring war in April 1917.
Very little changed in the employment of blockades during World War II. In fact, the blockade strategies largely mirrored those of World War I. The British employed a distant blockade of Germany that observed to some degree the authority of international law. The Germans again employed a submarine blockade of Britain and developed it further. Technological improvements in submarine designs between the wars allowed a widening of the war zone to include the entire Atlantic Ocean.
The Germans may have been the creators of the submarine blockade strategy, but the most successful use of it came in the Pacific theater with the U.S. submarine campaign against Japan. At the beginning of the war, the Japanese possessed six million tons of merchant shipping. They built an additional two million during the war. The American submarine blockade accounted for five million tons of the eight million tons sunk during the war, thus economically starving Japan.
The use of blockades has continued in the postwar years and has changed substantially from past uses. In terms of deployment, blockades now vary between close and distant ones based on the situation. The U.S. naval blockade of Cuba during the 1962 Cuban Missile Crisis employed a combination of both strategies. The same situation held true for the U.S. blockade of the Democratic Republic of Vietnam (North Vietnam) during the Vietnam War (1964–1975). These endeavors also used a combination of submarines and surface vessels instead of only one or the other.
International law and neutral rights also altered blockades with the creation of the United Nations in 1946. Postwar blockades have seen many more restrictions on their use, and in the recent past they have had more of a diplomatic than a military function.
The most recent naval blockade reveals how far the operation has evolved and once again brings into question its future use. In the Gulf War (1990–1991), the navies of the coalition against Iraq deployed a blockade of the Persian Gulf and the Red Sea. It had little effect on Iraqi wartime operations. International law made the blockade more humane because it allowed goods with a civilian use to pass into Iraq, and any violation risked condemnation by the United Nations. But this produced the same problem that forced the British to remove these restrictions during World War I in order to make their blockade effective. Blockades, in the age of total war, are directed at civilian and soldier alike to cripple a country’s war effort. Limited blockades cannot accomplish the strategic goals of the endeavor: the total destruction of the civilian and government sectors of a country’s economy in order to cripple its capacity to wage war.
Cable, James. The Political Influence of Naval Force in History. New York: St. Martin’s Press, 1998.
Hampshire, Cecil A. The Blockaders. London: William Kimber, 1980.
Harding, Richard. Sea Power and Naval Warfare, 1650-1830. Annapolis, MD: Naval Institute Press, 1999.
Jane, Fred T. The British Battle-Fleet: Its Inception and Growth throughout the Centuries. London: S. W. Partridge and Co., 1912.
How Britain Won the War of 1812: The Royal Navy’s Blockades of the United States, 1812-1815 by Brian Arthur