While the U.S. Navy, the Royal Navy and the Imperial Japanese Navy developed mature Fleet Air Arms and the French Navy experimented with the conversion of a Normandie class battleship hull into a carrier the Bearn the German Kriegsmarine and Italian Royal Navy the Regio Marina lagged behind. The Italian effort was hobbled by inter-service rivalries and doctrinal debates as well as political battles. As a result the Italians maintained a Seaplane Carrier until Mussolini decided in favor of a carrier. In Germany the effort was precluded by the terms of the Treaty of Versailles. In 1935 the Anglo-German Naval Treaty allowed the Germans to build carriers up to 35,000 tons displacement and the same year Hitler announced that Germany would build aircraft carriers. German Naval and Luftwaffe Officers travelled to Japan in 1935 to study the Japanese Carrier Akagi and the German Carrier Flugzugträger A later the Graf Zeppelin was laid down a year later.
The Italian Aircraft Carrier Aquila
Neither ship would ever become operational. The Italian ship named Aquila which was converted from the Ocean Liner Roma was begun in 1941 and by 1943 was nearing completion and already her static tests when Italy surrendered and she was commandeered by the Germans. Damaged by an allied air attack in 19on 44 she was partially scuttled on 19 April 1945. Aquila was salvaged and consideration was given to completing her after the war but she was scrapped in 1951.
Incomplete Aquila in German hands 1944
Reggiane Re.2001 Falco II
As a carrier Aquila displaced 28,000 tons full load and would have been capable of a maximum speed of 30 knots. She was designed to carry an air group of 51 Reggianne Re.2001 OR Serie II figher-bomber/torpedo bombers able to carry a able to carry a 600 kg torpedo or bomb. Had she been started in 1938 or 1939 instead of 1941 she might have been completed in time to be of assistance to the Italian Navy in its operations against the Royal Navy in the Mediterranean.
The Kriegsmarine Carrier Graf Zeppelin
The Germans faced their own challenges and despite the fact that Graf Zeppelin was launched on 8 December 1938 she was never completed and never achieved an operational status. Part of the problem was the weakness of the Kreigsmarine in relation to the other services, especially Goering’s Luftwaffe which maintained control of all German aircraft design, construction and operation. The other major issue was the lack of experience the Germans had in carrier design or construction which resulted in a number of retrofits which lasted until 1943 when she was nearly complete. At that point in time Hitler now thoroughly disillusioned with the Kriegsmarine surface units suspended her construction. She was scuttled in April 1945 before she could be captured by the Soviets. The Soviet Union would study her and use her in ordnance testing to see what kind of damage a carrier might absorb. She sank following being hit by 24 bombs, projectiles and two torpedoes.
The incomplete Graf Zeppelin
As a carrier Graf Zeppelin was 33,550 tons and would have capable of 35 knots with a 9,000 mile cruising range at 19 knots. Her air group would have been comprised of 30 Bf 109T fighters and 12 Ju 87 dive bombers.
Bf 109 T
The completion of either of these ships by the Axis Powers would probably not altered the course of the war but would have been an interesting footnote to history had they become operational and participated in any action against Allied Carriers.
The Inglorius Padre Steve's World 
Padre- You need to check out the following site:
http://www.phpbbplanet.com/warshipprojects/index.php?sid=b4681492ca18fbaeee9b7dfe4f0ab7bb&mforum=warshipprojects
It is a discussion board for all types of ships that fall into the “never were” category – designs like the Graf Zeppelin, that were laid down but not finished, designs like the USS Montana, that were fully laid out on paper but not built, and all sorts of projects ranging from full paper designs to sketches on napkins. There is TONS of information about these two carrier on the site. You can browse anonymously, or sign up for free to post. It may appear daunting at first, but the gang are pretty friendly, and if they don’t know about it, it probably didn’t exist. If you sign up, tell 1BigRich (one of the board monitors) that I sent you!
It would have failed. The Germans & Italians had NO experience in Carrier ops.
Probably so, both too little and too late. Graf Zeppelin was an interesting design, but the Germans didn’t have the capacity to have a task force that could range about the Atlantic and they did not have an efficient fleet train. Likewise they put nothing into carrier aircraft. The Italians were also too late. Had they build Aquila in the late 1920s or early 1930s with an air group and confined her to the Mediterranean she might have made a difference. But you cannot start something from nothing with no experience and expect it to succeed.you are absolutely correct.