Anti-submarine warfareAnti-submarine warfare (ASW, or in the older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typically carried out to protect friendly shipping and coastal facilities from submarine attacks and to overcome blockades. Successful ASW operations typically involved a combination of sensor and weapon technologies, along with effective deployment strategies and sufficiently trained personnel.
Unrestricted submarine warfareUnrestricted submarine warfare is a type of naval warfare in which submarines sink merchant ships such as freighters and tankers without warning, as opposed to attacks per prize rules (also known as "cruiser rules") that call for warships to search merchantmen and place crews in "a place of safety" (for which lifeboats do not qualify, except under particular circumstances) before sinking them, unless the ship shows "persistent refusal to stop ... or active resistance to visit or search".
Allied submarines in the Pacific WarAllied submarines were used extensively during the Pacific War and were a key contributor to the defeat of the Empire of Japan. During the war, submarines of the United States Navy were responsible for 56% of Japan's merchant marine losses; other Allied navies added to the toll. The war against shipping was the single most decisive factor in the collapse of the Japanese economy. Allied submarines also sank a large number of Imperial Japanese Army (IJA) troop transports, killing many thousands of Japanese soldiers and hampering the deployment of IJA reinforcements during the battles on the Pacific islands.
Q-shipQ-ships, also known as Q-boats, decoy vessels, special service ships, or mystery ships, were heavily armed merchant ships with concealed weaponry, designed to lure submarines into making surface attacks. This gave Q-ships the chance to open fire and sink them. The use of Q-ships contributed to the abandonment of cruiser rules restricting attacks on unarmed merchant ships and to the shift to unrestricted submarine warfare in the 20th century.
Second Happy TimeThe Second Happy Time (Zweite glückliche Zeit; officially Operation Paukenschlag ("Operation Drumbeat"), and also known among German submarine commanders as the "American Shooting Season") was a phase in the Battle of the Atlantic during which Axis submarines attacked merchant shipping and Allied naval vessels along the east coast of North America. The First Happy Time was in 1940–1941 in the North Atlantic and North Sea. Adolf Hitler and Benito Mussolini declared war on the United States on 11 December 1941, and as a result their navies could begin the Second Happy Time.
Battle of the AtlanticThe Battle of the Atlantic, the longest continuous military campaign in World War II, ran from 1939 to the defeat of Nazi Germany in 1945, covering a major part of the naval history of World War II. At its core was the Allied naval blockade of Germany, announced the day after the declaration of war, and Germany's subsequent counter-blockade. The campaign peaked from mid-1940 through to the end of 1943.
Military strategyMilitary strategy is a set of ideas implemented by military organizations to pursue desired strategic goals. Derived from the Greek word strategos, the term strategy, when first used during the 18th century, was seen in its narrow sense as the "art of the general", or "the art of arrangement" of troops. and deals with the planning and conduct of campaigns, the movement and disposition of forces, and the deception of the enemy. The father of Western modern strategic studies, Carl von Clausewitz (1780–1831), defined military strategy as "the employment of battles to gain the end of war.
