The main battery turrets had thick faces and 70 mm thick sides. Construction and conversion Seydlitz was ordered by the Kriegsmarine from the Deschimag shipyard in Bremen. Seydlitz was originally designed as a light cruiser version of the Admiral Hipper-class heavy cruisers, armed with twelve guns instead of the Admiral Hippers eight guns. The Kriegsmarine decided, however, to complete the ship identically to Admiral Hipper on 14 November 1936. Her keel was laid on 29 December 1936, under construction number 940. The ship was launched on 19 January 1939, but after the outbreak of World War II in September 1939, work was halted when the ship was approximately 95 percent complete. Following the loss of the battleship in May 1941, during which British aircraft carriers proved instrumental, and the near torpedoing of her sistership in March 1942, the Kriegsmarine became convinced of the necessity of acquiring aircraft carriers. Work on the purpose-built carrier , which had been halted in April 1940, was resumed in March 1942. The Kriegsmarine also decided to convert a number of vessels into auxiliary aircraft carriers. Seydlitz was among the ships selected for conversion, along with several passenger liners. At the same time as construction of Graf Zeppelin resumed, conversion work began on Seydlitz. The majority of the superstructure was cut away, with the exception of the funnel, to prepare for the installation of a flight deck and an aircraft hangar. In total, approximately of material from the ship was removed. The flight deck was to have been long and wide. The hangar was long and wide forward and wide amidships and aft. Her armament was reduced to an anti-aircraft battery of ten 10.5 cm L/65 guns in twin mounts, two forward of the conning tower and three aft, ten 3.7 cm guns in dual mounts, and twenty-four 2 cm guns in quadruple mounts. Seydlitzs air complement was to have consisted of ten Bf 109 fighters and ten Ju 87 Stuka divebombers. The Bf 109 fighters were a navalized version of the "E" model, designated as Bf 109T. Their wings were longer than the land-based model to allow for shorter take-off. The Ju 87 type selected was to have been the "E" variant, which was a navalized version of the Ju 87D, and were modified for catapult launches and were equipped with arresting gear. Work was ceased in June 1943, before the conversion was completed. The