The head of the military historical service of the US Army, Earl Ziemke, in his book talks about two large-scale campaigns carried out by Nazi Germany in the northern theater of operations. The first began in April 1940 against Denmark and Norway, and the second was waged jointly with Finland against the Soviet Union. The territory of military operations covered the space from the North Sea to the Arctic Ocean and from Bergen on the western coast of Norway to Petrozavodsk, the former capital of the Karelo-Finnish Soviet Socialist Republic. Hitler attached great importance to this area and considered it the cornerstone of the future empire. Two armies with a total strength of more than half a million bayonets were concentrated here. The research was carried out on the basis of materials from captured archives of the German ground forces and naval forces. Memoirs and other written testimonies of German officers who took part in the combat operations of these campaigns were widely used.