U-boatU-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic-warfare role (commerce raiding) and enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada and other parts of the British Empire, and from the United States, to the United Kingdom and (during the Second World War) to the Soviet Union and the Allied territories in the Mediterranean.
Attack on Pearl HarborThe attack on Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the U.S. naval base at Pearl Harbor in Honolulu, Hawaii, just before 8:00a.m. (local time) on Sunday, December 7, 1941. The United States was a neutral country at the time; the attack led to its formal entry into World War II on the side of the Allies the next day. The Japanese military leadership referred to the attack as the Hawaii Operation and Operation AI, and as Operation Z during its planning.
Naval mineA naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any vessel or a particular vessel type, akin to anti-infantry or anti-vehicle mines. Naval mines can be used offensively, to hamper enemy shipping movements or lock vessels into a harbour; or defensively, to protect friendly vessels and create "safe" zones.
Allies of World War IIThe Allies, formally referred to as the United Nations from 1942, were an international military coalition formed during the Second World War (1939–1945) to oppose the Axis powers, led by Nazi Germany, the Empire of Japan, and the Kingdom of Italy. Its principal members by the end of 1941 were the United Kingdom, United States, Soviet Union, and China. Membership in the Allies varied during the course of the war. When the conflict broke out on 1 September 1939, the Allied coalition consisted of the United Kingdom, France, and Poland, as well as their respective dependencies, such as British India.
BattleshipA battleship is a large armored warship with a main battery consisting of large caliber guns. It dominated naval warfare in the late 19th and early 20th centuries. The term battleship came into use in the late 1880s to describe a type of ironclad warship, now referred to by historians as pre-dreadnought battleships. In 1906, the commissioning of into the United Kingdom's Royal Navy heralded a revolution in the field of battleship design.
