Blockade

A blockade is an effort to cut off supplies, war material or communications from a particular area by force, either in part or totally. A blockade should not be confused with an embargo or sanctions, which are legal barriers to trade. It is also distinct from a siege in that a blockade is usually directed at an entire country or region, rather than a fortress or city. While most blockades historically took place at sea, blockade is still used on land to prevent someone coming into a certain area. A blockading power can seek to cut off all maritime transport from and to the blockaded country; although stopping all land transport to and from an area may also be considered a blockade. Blockades restrict the trading rights of neutrals, who must submit for inspection for contraband, which the blockading power may define narrowly or broadly, sometimes including food and medicine. In the 20th century air power has also been used to enhance the effectiveness of the blockade by halting air traffic within the blockaded airspace. Close patrol of hostile ports, in order to prevent naval forces from putting to sea, is also referred to as a blockade. When coastal cities or fortresses were besieged from the landward side, the besiegers would often blockade the seaward side as well. Most recently, blockades have sometimes included cutting off electronic communications by jamming radio signals and severing undersea cables. Although primitive naval blockades had been in use for millennia, the first successful attempts at establishing a full naval blockade were made by Admiral of the Fleet Edward Hawke during the Seven Years' War (1754–1763). Following the British naval victory at Quiberon Bay, which ended any immediate threat of a major invasion of the British Isles, the British implemented a tight economic blockade on the French coast. This began to starve French ports of commerce, further weakening France's economy. Hawke took command of the blockading fleet off Brest and extended the blockade of the French coast from Dunkirk to Marseilles. The British were able to take advantage of the Navy's position to develop plans for amphibious landings on the coast. However, these plans were eventually abandoned, due to the formidable logistical challenge this would have posed. The strategic importance of the blockade was cemented during the Revolutionary and Napoleonic Wars, during which successful blockades on France were imposed by the Royal Navy, leading to major economic disruptions. The Union blockade of southern ports was a major factor in the American Civil War, as was the failure of the U-boat blockade in World War I and again in World War II. Julian Corbett and Admiral Mahan emphasized that naval operations were chiefly to be won by decisive battles and blockade. A close blockade entails placing warships within sight of the blockaded coast or port, to ensure the immediate interception of any ship entering or leaving. It is both the most effective and the most difficult form of blockade to implement. Difficulties arise because the blockading ships must remain continuously at sea, exposed to storms and hardship, usually far from any support, and vulnerable to sudden attack from the blockaded side, whose ships may stay safe in harbor until they choose to come out. In a distant blockade, the blockaders stay well away from the blockaded coast and try to intercept any ships going in or out. This may require more ships on station, but they can usually operate closer to their bases, and are at much less risk from enemy raids. This was almost impossible prior to the 16th century due to the nature of the ships used.