What was the German tactic of sudden, swift attacks called?

The German tactic of sudden, swift attacks was called "Blitzkrieg," which is a German term literally translating to "lightning war." This military strategy involved quick and surprising attacks combining fast-moving, coordinated assaults by airplanes, tanks, artillery, and mechanized infantry, aiming to break through enemy lines and encircle them. The key was to strike hard and fast, creating shock and disorganization among enemy forces, which often led to rapid victories.

Blitzkrieg became synonymous with Germany's military operations early in World War II, particularly during the invasions of Poland in 1939, France in 1940, and the initial phase of the invasion of the Soviet Union in 1941. It emphasized the importance of speed, coordination, and the element of surprise, bypassing and encircling enemy strongpoints and striking at vital enemy infrastructure and supply lines.

The innovation of the Blitzkrieg strategy lay in its effective use of the latest technology of the time, including advancements in communications, which allowed for better coordination between different branches of the military. Air power played a crucial role, with dive-bombers such as the Ju-87 Stuka being used to provide close air support to ground troops. Meanwhile, the mechanized panzer divisions, with their tanks and armored vehicles, would punch through defensive lines and proceed with rapid advances.

In essence, Blitzkrieg fundamentally changed the nature of warfare in the early 20th century. However, it relied on certain conditions to be effective, such as clear weather for air superiority and relatively open and unfortified terrain to allow for the mobility of armoured and motorized units. When faced with harsh winter conditions, urban environments, and prepared defensive positions, Blitzkrieg tactics were significantly less effective, as seen later in the war on the Eastern Front and during the Allied advances through Europe after the D-Day landings.