European Theatre of World War II in the context of "Operation Clausewitz"

The Heinkel He 111 is a German airliner and medium bomber designed by Siegfried and Walter Günter at Heinkel Flugzeugwerke in 1934. Through development, it was described as a wolf in sheep's clothing. Due to restrictions placed on Germany after the First World War prohibiting bombers, it was presented solely as a civil airliner, although from conception the design was intended to provide the nascent Luftwaffe with a heavy bomber.

Perhaps the best-recognised German bomber of World War II due to the distinctive, extensively glazed "greenhouse" nose of the later versions, the Heinkel He 111 was the most numerous Luftwaffe bomber during the early stages of the war. It fared well until it met serious fighter opposition during the Battle of Britain, when its defensive armament was found to be inadequate. As the war progressed, the He 111 was used in a wide variety of roles on every front in the European theatre. It was used as a strategic bomber during the Battle of Britain, a torpedo bomber in the Atlantic and Arctic, and a medium bomber and a transport aircraft on the Western, Eastern, Mediterranean, Middle Eastern, and North African Front theatres.

The 21st Army Group was a British headquarters formation formed during the Second World War. It controlled two field armies and other supporting units, consisting primarily of the British Second Army and the First Canadian Army. Established in London during July 1943, under the command of Supreme Headquarters Allied Expeditionary Force (SHAEF), it was assigned to Operation Overlord, the Western Allied invasion of Europe, and was an important Allied force in the European Theatre. At various times during its existence, the 21st Army Group had additional British, Canadian, American, and Polish field armies or corps attached to it. The 21st Army Group operated in Northern France, Luxembourg, Belgium, the Netherlands and Germany from June 1944 until August 1945, when it was renamed the British Army of the Rhine (BAOR).

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.