Changing priorities during World War 2 derailed any hopes that Nazi Germany would ever field a viable aircraft carrier in combat. Twocarriers of the Graf Zeppelin-class were planned by Germany prior to the war in the 1930s. Deutsche Werke was selected as the primary builder and the keel of Graf Zeppelin ("Flugzeugtrager A") was laid down on December 28th, 1936. She was launched on December 8th, 1938 with World War 2 set to begin in September of the following year.
Like other ocean-going powers of the world in the 1930s, a rearming Germany sought to have a fleet capable of multiple mission types so this required a broad balance of surface warships and undersea assets tied together by logistically-minded types. With this in mind, German military power could be projected well beyond the confines of the German coastline and its available seas. This thinking gave rise to the need for aircraft carriers to compete with British and American designs of the time.
However, Graf Zeppelin, named after Count Ferdinand von Zeppelin (1938-1917) of World War 1 fame, was only 3/4 complete by the time World War arrived in Europe again. The invasion of Poland by Germany on September 1st, 1939 marked the official start of the Grand Conflict and immediately strained German naval resources to the extreme. The country's commitment to the war was such that priorities were often forced to be shifted much to the detriment of projects such as Graf Zeppelin and her sister. While she was eventually launched, she was not completed nor commissioned for service as the German Navy decided a larger U-boat (submarine) fleet was of better value as the war drew on. Graf Zeppelin was restricted to Baltic waters for its part in the war and, with the German surrender an eventuality in 1945, the hull was scuttled by her caretakers near Stettin in March of 1945. The victorious Soviets eventually claimed her and were able to raise the ship where she lay - only to expend her in weapons testing on August 16th, 1947. Her remains were discovered by a Polish oil industry crew in July of 2006.
Graf Zeppelin marked the only serious aircraft carrier project undertaken by the Germans in World War 2. The second incomplete carrier of the group, to be called Peter Strasser ("Flugzeugtrager B"), was scrapped in 1949.
Under the terms of the 1935 Anglo-German Naval agreement with Britain, the German Navy was restricted in its allowed tonnage regarding warships (as relative to the Royal Navy) so carriers displacing 20,000 tons were authorized. German designers were not inherently experienced in aircraft carrier design so flaws were evident in this first attempt as the need for high speed, good protection and heavy armament was lacking. Good handling at-sea while undertaking high speed maneuvers was required and the design developed a long hull with adequate freeboard. The flight deck proved heavy so additional hull bulges were added for strength and stability and the flight deck stopped short of the bow as in some of the contemporary Japanese carrier designs (indeed the Germans were influenced by Japanese carrier designs of the period). The tonnage of the carriers was increased by some 50% during the course of construction by the Germans but this was not challenged by the international community at the time.
As designed, Graf Zeppelin utilized much of the same qualities seen in foreign aircraft carrier types. She had a flat, straight-through flight deck running from bow-to-stern with the island superstructure held off to the starboard side of the ship. The island also integrated the smoke funnel. The hull was very much like those seen in other surface combatants with a tapered bow and rounded stern. Three powered hangar elevators would give the warplanes access to the flight deck as needed. A pair of catapults would be featured over the bow. Armor protection ranged from 3.9" at the belt to 1.8" along the flight deck. The main deck was covered over in up to 2.4" of protection.
Installed power was a quadruple geared steam turbine arrangement outputting 200,000 horsepower to 4 x shafts under stern. The Brown, Boveri & Cie turbines were fed by 16 x LaMont oil-fired, high-pressure boiler units. In optimal conditions, the carrier could reach an estimated 33 knots out to a range of 8,000 nautical miles. Dimensions included a length of 861.2 feet with a beam of 118.8 feet and a draught of 27.10 feet. Displacement reached 34,088 tons under full load. Aboard was to be a crew of 1,720 personnel.
Installed armament was to be 16 x 150mm SK C/28 guns, 12 x 105mm SK C/33 guns, 22 x 37mm SK C/30 guns and 28 x 20mm FlaK guns - all designed to handle incoming close-in threats at range.
The air arm was to consist of up to forty-two combat warplanes made up of fighters and dive bombers. Navalized versions of the Messerschmitt BF 109 fighter as well as the Junkers Ju 87 "Stuka" dive bomber were considered. For the torpedo delivery role, the Fieseler Fi 167 biplane was to be taken on. A mix of such aircraft was to stock the hangars of Graf Zeppelin. It is of note that the Luftwaffe (air service) would not welcome a shift in control of navy warplanes to the German Navy - a rivalry seen amongst many global armed services for decades.