 Considered an essential part of the Atlantic Wall in anticipation of an Allied invasion, the fortifications in Norway were primarily based around coastal artillery, but also included elements of anti-aircraft batteries, tank and infantry forces.There were as many as 400,000 German troops in Norway during the occupation, a large proportion of whom were dedicated to the defence of the Northern flank of the Atlantic wall.The scope of "Festung Norwegen" originally included the entire coastal perimeter of Norway, from the Oslofjord around the southern coast and to the border with the Soviet Union.