The German Wehrmacht conducted two distinct, though not unrelated and at times overlapping types of warfare between 1939 and 1945. One was based on massive, concentrated, and well-coordinated attacks along narrow fronts, leading to encirclements of large enemy forces and aimed at achieving a rapid military and political disintegration of the opponent by undermining both his logistical apparatus and psychological determination at a minimum cost to the attacking force. The other constituted a stubborn and costly defence, along huge, static, or gradually retreating fronts, normally launching only local attacks and counter-attacks with relatively limited elements of the armed forces, and relying increasingly on fortifications and doggedness rather than on speed and daring. The first type, which came to be known as Blitzkrieg, or lightning war, since it assumed a brief, though intense military confrontation, called for the preparation of limited stocks of armaments (without any major, long-term changes in the economy) needed for the implementation of such shock tactics, namely tanks, armoured personnel carriers, motorised artillery, and anti-aircraft guns, as well as fighter planes and tactical support light and medium bombers.