The World War I era Pre-dreadnought battleships Schlesien and Schleswig-Holstein were used mainly as training ships, although they also participated in several military operations, with the latter bearing the distinction of firing the opening shots of WWII. Zähringen and Hessen were converted into radio-guided target ships in 1928 and 1930 respectively. Hannover was decommissioned in 1931 and struck from the naval register in 1936.