By 1938, it became clear to Admiral Erich Raeder that Hitler's aggressive foreign policy would bring conflict with Britain. He therefore decided that a significantly larger force of armored ships would be necessary to execute an effective commerce raiding campaign against the British. Raeder's intention to fight a commerce war against Britain was the basis for Plan Z, which included twelve ships of the P-class design. The design work on the new ships proceeded in parallel with work on the design. Experiments were conducted on at least nine different design proposals between March 1938 and December 1939. The designs varied somewhat in terms of dimensions as well as armament; some of the designs featured three 28 cm triple turrets.