He fought in World War I and after the end of hostilities, was retained in the postwar Reichswehr (Imperial Defence).

[1] On the outbreak of World War II, Prittwitz led the brigade in the invasion of Poland during which it was heavily engaged.

[2][note 1] Along with the rest of the division, Prittwitz's brigade was then transferred to the west and attached to Generalleutnant Heinz Guderian's XIX Motorised Corps.

[note 2] When the Germans invaded France and the Low Countries, the brigade performed well at Sedan and then advanced to the coast and reached Dunkirk.

[2] When the Panzerwaffe branch of the Heer (Army) expanded, Prittwitz was selected to lead the 14th Panzer Division on 1 October 1940.