Battle of the Atlantic

The Battle of the Atlantic was the longest continuous military campaign[4][5] in World War II, running from 1939 to the defeat of Germany in 1945. At its core was the Allied naval blockade of Germany, announced the day after the declaration of war, and Germany's subsequent counter-blockade. It was at its height from mid-1940 through to the end of 1943. The Battle of the Atlantic pitted U-boats and other warships of the Kriegsmarine (German Navy) and aircraft of the Luftwaffe (German Air Force) against Allied merchant shipping. The convoys, coming mainly from North America and mainly going to the United Kingdom and the Soviet Union, were protected for the most part by the British and Canadian navies and air forces. These forces were aided by ships and aircraft of the United States from September 13, 1941.[6] The Germans were joined by submarines of the Italian Royal Navy (Regia Marina) after their Axis ally Italy entered the war on June 10, 1940. As an island nation, the United Kingdom was highly dependent on imported goods. Britain required more than a million tons of imported material per week in order to be able to survive and fight. In essence, the Battle of the Atlantic was a tonnage war: the Allied struggle to supply Britain and the Axis attempt to stem the flow of merchant shipping which enabled Britain to keep fighting. From 1942 onwards, the Germans also sought to prevent the build-up of Allied supplies and equipment in the British Isles in preparation for the invasion of occupied Europe. The defeat of the U-boat threat was a pre-requisite for pushing back the Germans. Winston Churchill was later to state:[7] The Battle of the Atlantic was the dominating factor all through the war. Never for one moment could we forget that everything happening elsewhere, on land, at sea or in the air depended

ultimately on its outcome. The outcome of the battle was a strategic victory for the Allies—the German blockade failed—but at great cost: 3,500 merchant ships and 175 warships were sunk for the loss of 783 U-boats. The name "Battle of the Atlantic" was coined by Winston Churchill in February 1941.[8] It has been called the "longest, largest, and most complex" naval battle in history.[9] The campaign began immediately after the European war began and lasted six years. It involved thousands of ships in more than 100 convoy battles and perhaps 1,000 single-ship encounters, in a theatre covering thousands of square miles of ocean. The situation changed constantly, with one side or the other gaining advantage, as new weapons, tactics, counter-measures, and equipment were developed by both sides. The Allies gradually gained the upper hand, overcoming German surface raiders by the end of 1942 (withdrawn on Hitler's orders) and defeating the U-boats by mid-1943, though losses to U-boats continued to war's end.Following the use of unrestricted submarine warfare by Germany in the First World War, countries tried to limit, even abolish, submarines. The effort failed. Instead, the London Naval Treaty required submarines to abide by "cruiser rules", which demanded they surface, search[12] and place ship crews in "a place of safety" (for which lifeboats did not qualify, except under particular circumstances)[13] before sinking them, unless the ship in question showed "persistent refusal to stop...or active resistance to visit or search".[14] These regulations did not prohibit arming merchantmen,[15] but doing so, or having them report contact with submarines (or raiders), made them de facto naval auxiliaries and removed the protection of the cruiser rules.[16] This made restrictions on submarines effectively moot.