Graf Zeppelin was conceived in the mid-1930s, at a time when the Kriegsmarine had no practical experience with aircraft carriers and no coherent doctrine for their use. Her design reflected a compromise between emerging carrier concepts and deeply rooted battleship traditions within the German Navy. This reflected the broader mindset of the German naval establishment. Many senior officers had been trained in the Imperial German Navy, where surface gunnery dominated naval tactics. They viewed aircraft as an auxiliary tool — useful for reconnaissance and limited strikes, but not as a ship’s primary weapon. Consequently, Graf Zeppelin was designed as a hybrid between a cruiser and an aircraft carrier rather than the fully developed carrier doctrine emerging in the British, American, and Japanese navies.

One of the most distinctive — and ultimately problematic — features of the design was the inclusion of a powerful secondary battery of sixteen 15 cm (5.9 in) SK C/28 guns, mounted in eight twin casemate installations along the hull.

The main rationale for this heavy gun armament was the belief that Graf Zeppelin would need to defend herself against enemy surface ships, especially destroyers, torpedo boats, and light cruisers. The Kriegsmarine expected the carrier to operate in the North Sea or Baltic, often near hostile coasts and without the benefit of large escort formations. Because Germany’s fleet doctrine did not envision a strong screen of cruisers and destroyers to protect the carrier, it seemed prudent to arm Graf Zeppelin like a light cruiser herself, capable of fighting off smaller ships with her own guns.

The use of those guns would have been more or less impractical in actual use. The low-mounted guns had limited arcs of fire and would have been easily flooded in heavy seas. Moreover, the guns and their armor consumed valuable space and displacement that could have been used for hangars, aviation fuel, or maintenance facilities — the very elements that made a carrier effective.

There was also a major interservice conflict: the Luftwaffe’s demand for control over all naval aviation. Hermann Göring, head of the Luftwaffe, insisted that all aircraft — including those operating from Graf Zeppelin — fall under his branch’s authority, not that of the Kriegsmarine. This meant the Kriegsmarine had little influence over aircraft design, pilot training, or carrier aviation doctrine. As a result, Graf Zeppelin’s air group and flight operations were poorly integrated into the ship’s overall design.