Following World War I, the Italian Royal Navy (Regia Marina) began exploring the use of ship-borne aircraft by converting the merchant ship Città di Messina into the twin-catapult-equipped seaplane tender Giuseppe Miraglia.

More than anything else, Italy's limited industrial capacity, inadequate shipyard space and lack of financial capital prevented her from building the kind of well-balanced fleet envisioned by her naval theorists.

Instead, Italy modernized four older battleships (Cavour and Cesare in 1933, Doria and Duilio between 1937 and 1940), and began the construction of four new ones (Vittorio Veneto and Littorio in 1934, and later the Roma and Impero in 1938).

[4] Because the Regia Marina was expected to operate primarily in the relatively narrow confines of the Mediterranean and not on the world's oceans, the navy's lack of a fleet air arm seemed a tolerable omission (especially given that carriers were an expensive and unproven commodity at the time).

[5] Nevertheless, in June 1940, shortly after Italy's entry into the war, Mussolini sanctioned the preliminary project for a conversion of the 30,800 long tons (31,294 t), 21 kn (39 km/h; 24 mph) ocean liner Roma into an auxiliary carrier, featuring a flush deck and a small hangar.

These included excessive cost; technical obstacles involving development of catapults, arrester gear and elevators; an estimated two-year development time for folding-wing aircraft; the time needed for studying the effects of air turbulence over the flight deck from an island superstructure; problems the Germans were encountering in the construction of their own aircraft carrier, Graf Zeppelin; and recent accounts of the heavy damage inflicted by German dive bombers on the British carrier Illustrious, graphically demonstrating the vulnerability of carriers operating in the Mediterranean.

[6] In order improve resistance to underwater damage, the ship was heavily subdivided with 18 watertight bulkheads extending up to 'C' or 'D' deck, 11 of which were double.

The fuel tanks copied British practice and consisted of cylinders or coffer dams separated from the ship's hull by water-filled compartments.

The four engines survived the conflict and after the war, they were reused as pairs of two on the twin ocean liners [8] Self-propulsion tests at the Freude tank at La Spezia in January 1942 indicated that for a trial displacement of 26,700 tons, a speed of 29 knots could be achieved with 132,660 shp.

[13] The flight deck ended short of the bows but overhung the stern, where it featured a pronounced round-down to improve air flow.

One was directly amidships and the second another 90 ft (27 m) forward, thus placing them far enough from the aft arrester wires that both could be used for striking down aircraft into the hangar immediately after a landing.

[6] Two German-supplied Demag compressed air-driven catapults, each capable of launching one aircraft every 30 seconds, were installed parallel to each other at the forward end of the flight deck.

Aquila′s engines and catapults were successfully tested in August 1943 but the arresting gear installed on the carrier, consisting of four cables, initially failed to work properly.

It was therefore proposed that aircraft taking off from Aquila would, after performing their mission, fly back to the nearest land-based airfield or simply ditch in the sea, a serious and embarrassing limitation on her capabilities as a fleet carrier.

[15] Italian and German technicians labored for months at the Perugia Sant'Egidio airfield on a mock-up of Aquila's flight deck and by March 1943 the heavily modified arresting gear was deemed usable.

[6] Throughout 1942 and 1943, trials were conducted at Perugia and Guidonia—the Regia Aeronautica′s equivalent to the German Luftwaffe′s test facility at Rechlin—to find aircraft suitable for conversion to carrier use.

[13] In March 1943, German engineers and instructors with experience on Graf Zeppelin arrived to advise on aircraft testing and to help train future carrier pilots culled from 160 Gruppo C.T.

They brought with them examples of a Junkers Ju 87C Stuka dive bomber (a navalized version with folding wings, arrester hook and catapult attachment points) and an Arado Ar 96B single-engine trainer.

After conducting comparative flight trials, the Italians eventually settled on the Re.2001 as their standard carrier fighter/fighter-bomber and even the Germans concluded it had better potential than their own counterpart, the Messerschmitt Bf 109T.

[18] Near the end of the war, the royalist Italian Co-belligerent Navy feared the Germans might use Aquila as a blockship to the entrance to Genoa harbor, just as they did with her sister ship, the converted aircraft carrier Sparviero (formerly the ocean liner Augustus) a few months prior.

Mariassalto divers from the former Decima Flottiglia MAS then executed a daring sabotage operation on the night of the 18 and 19 April 1945, in which they partially sunk Aquila in a harmless location.