Naval history of World War II in the context of "Battle of the Atlantic"

Karl Dönitz (German: [ˈdøːnɪts] ; 16 September 1891 – 24 December 1980) was a German grand admiral and convicted war criminal who, following Adolf Hitler's suicide during the Second World War in April 1945, succeeded him as head of state of Nazi Germany. He held the position until the dissolution of the Flensburg Government following Germany's unconditional surrender to the Allies weeks later. As Supreme Commander of the Navy beginning in 1943, he played a major role in the naval history of the war.

He began his career in the Imperial German Navy before the First World War. In 1918 he was commanding UB-68, and was captured as a prisoner of war by British forces. As commander of UB-68, he attacked a convoy in the Mediterranean while on patrol near Malta. Sinking one ship before the rest of the convoy outran his U-boat, Dönitz began to formulate the concept of U-boats operating in attack groups Rudeltaktik (German for "pack tactic", commonly called a "wolfpack") for greater efficiency, rather than operating independently.

Chester William Nimitz (/ˈnɪmɪts/; 24 February 1885 – 20 February 1966) was a fleet admiral in the United States Navy. He played a major role in the naval history of World War II as Commander in Chief, US Pacific Fleet, and Commander in Chief, Pacific Ocean Areas, commanding Allied air, land, and sea forces during World War II.

Nimitz was the leading U.S. Navy authority on submarines. Qualified in submarines during his early years, Nimitz later oversaw the conversion of these vessels' propulsion from gasoline to diesel, and then later was key in acquiring approval to build the world's first nuclear-powered submarine, USS Nautilus, whose propulsion system later completely superseded diesel-powered submarines in the United States. Beginning in 1917, Nimitz was the Navy's leading developer of underway replenishment techniques, the tool which during the Pacific war would allow the American fleet to operate away from port almost indefinitely. The chief of the Navy's Bureau of Navigation from 1939 to 1942, Nimitz served as the Chief of Naval Operations from 1945 until 1947. He was the United States' last surviving officer who served in the rank of fleet admiral. The USS Nimitz supercarrier, the lead ship of her class, is named after Nimitz.

Arctic naval operations of World War II were the World War II naval operations that took place in the Arctic Ocean, and can be considered part of the Battle of the Atlantic and/or of the European Theatre of World War II.

Pre-war navigation in the region focused on fishing and the international ore-trade from Narvik and Petsamo. Soviet settlements along the coast and rivers of the Barents Sea and Kara Sea relied upon summer coastal shipping for supplies from railheads at Arkhangelsk and Murmansk. The Soviet Union extended the Northern Sea Route past the Taymyr Peninsula to the Bering Strait in 1935. The Winter War of 1939-1940 between Finland and the Soviet Union opened the northern flank of the Eastern Front of World War II. The Arctic was initially dominated by the Soviet Northern Fleet of a few destroyers, with larger numbers of submarines, minesweepers, and torpedo cutters supported by icebreakers. The success of the 1940 German invasion of Norway provided the Kriegsmarine with naval bases from which capital ships might challenge units of the British Royal Navy Home Fleet. Luftwaffe anti-shipping aircraft of Kampfgeschwader 26 (KG 26) and Kampfgeschwader 30 (KG 30) operated intermittently from Norwegian airfields, while Küstenfliegergruppen aircraft including Heinkel He 115s and Blohm & Voss BV 138s undertook routine reconnaissance. Following the 1941 Axis invasion of the Soviet Union, the Allies initiated a series of Arctic convoys to bring military supplies to the Soviet Union in formations of freighters screened by destroyers, corvettes and minesweepers. Escorting cruisers typically maneuvered outside the formations, while a larger covering force including battleships and aircraft carriers often steamed nearby to engage Kriegsmarine capital ships or to raid the German naval bases in Norway.