Graf Zeppelin aircraft carrier was a much bigger waste of resources than all H-class battleships combined, because unlike them, it was about 80-85% complete by the time all work on the carrier has been stopped for good in February of 1943.
The biggest problem of the carrier was that the Kriegsmarine brass had an entirely wrong idea about its operational strategy. American, British and Japanese navies adopted the strategy of carrier groups (one or more carriers protected by cruisers and destroyers from enemy surface ships and thus armed only with AA guns), which allowed flight operations to continue without disruption and kept carriers out of undue risk of damage or sinking from surface action.
Graf Zeppelin was supposed to operate solo (or with minimum support) against enemy convoys and task forces. Consequently, it was not a “classic carrier” but essentially the “aircraft-carrying cruiser” armed with sixteen (!) 150mm guns.
And thus would have been an easy prey for American or British task forces as it (1) was no match for enemy battleships, battle cruisers heavy and possibly even cruisers due to its size, poor armor, relatively slow speed and poor maneuverability and (2) had too few aircraft to successfully engage even 2-3 escort carriers.
A combination of political infighting between the Kriegsmarine and the Luftwaffe, disputes within the ranks of the Kriegsmarine itself and Adolf Hitler’s waning interest all “conspired” against the carriers.
A shortage of workers and materials slowed construction still further and, in 1939, Kriegsmarine commander-in-chief Erich Raeder reduced the number of ships from four (stipulated by Plan Z) to two – Graf Zeppelin and Peter Strasser.
Even so, the Luftwaffe trained its first unit of pilots for carrier service and readied it for flight operations. However, with the advent of World War II, priorities predictably shifted to U-boat construction.
Consequently, Peter Strasser was broken up on the slipway while work on the other and Graf Zeppelin was continued tentatively but suspended in 1940. The air unit scheduled for her was disbanded at that time.
However, the decisive role of carrier-based aircraft in the Battle of Taranto, the pursuit of the German battleship Bismarck, the attack on Pearl Harbor and the Battle of Midway demonstrated conclusively the usefulness of aircraft carriers in modern naval warfare.
Which renewed Hitler’s interest in the solo remaining carrier so on his orders, work resumed on the remaining carrier. Still, progress was again delayed, this time by the demand for newer planes specifically designed for carrier use and the need for modernizing the ship in light of wartime developments.
The German naval staff hoped all these changes could be accomplished by April 1943, with the carrier’s first sea trials taking place in August that same year. However, by late January 1943 Hitler had become so disenchanted what he perceived as the poor performance of the surface fleet that he ordered all of its larger ships taken out of service and scrapped. So on February 2nd, 1943, construction on the carrier ended for good.
Graf Zeppelin languished for the next two years in various Baltic ports. On April 125th, 1945, it was scuttled at Stettin (now Szczecin, Poland), ahead of the advancing Red Army.
According to the agreement between the Soviet Union and the Allies, Graf Zeppelin should have been destroyed or scuttled into deep waters. However, the Soviet Navy had other things in mind for the vessel.
So, in their decision to repair what might have been their enemy’s only aircraft carrier, they refloated her on March of 1946 and she was towed from Poland to Leningrad (now St. Petersburg).
Unfortunately for them and for the embattled carrier, Soviet dictator did not believe in the value of the aircraft carrier (this was one of the few strategic mistakes that he made during his lifetime).
So the carrier was towed back to the Polish coast and became a practice target for Soviet warplanes and Naval ships. 24 bombs and projectiles later, she was still afloat. Eventually, two torpedoes finished her off and sent her down her watery grave.