The two Bismarck-class battleships followed in 1936; Bismarck was completed in 1940 and Tirpitz in 1941.[16] Plan Z was formulated in 1939 to rebuild the German navy; the plan called for six additional battleships of the H-39 class.[17] Two of them were laid down in mid-1939, though they were canceled within two months, due to the outbreak of World War II in September 1939.