The CVB-41 class vessels (then unnamed) were originally conceived in 1940 as a design study to determine the effect of including an armored flight deck on a carrier the size of the Essex class. The resulting calculations showed that the effect would be a reduction of air group size - the resulting ship would have an air group of 64, compared to 72 for the standard Essex class fleet carriers. The design was also heavily influenced by the wartime experience of the Royal Navy's armored carriers:
As a result of study of damage sustained by various British carriers prior to our entry into the war, two important departures from traditional U.S. Navy carrier design were incorporated in the CVB Class, then still under development. HMS ILLUSTRIOUS in an action off Malta on 1 January 1941 was hit by several bombs, three of which detonated in the hangar space. Large fires swept fore and aft among parked planes thereby demonstrating the desirability of attempting to confine the limits of such explosions and fires by structural sectionalization of the hangar space. On the CVB Class the hangar was therefore divided into five compartments separated by 40 and 50-pound STS division bulkheads extending from the hangar deck to the flight deck, each fitted with a large door suitable for handling aircraft. It is hoped that this sectionalization, in conjunction with sprinkler and fog foam systems, will effectively prevent fires from spreading throughout the hangar spaces, as occurred on FRANKLIN on 30 October and 19 March. The damage experiences of several British carriers, which unlike our own were fitted with armored flight decks, demonstrated the effectiveness of such armor in shielding hangar spaces from GP bombs and vital spaces below the hangar deck from SAP bombs. Accordingly, the CVB Class was designed with an armored flight deck consisting of 3-1/2-inch STS from frames 46 to 175 with a hangar deck consisting of two courses of 40-pound STS between frames 36 and 192. Although none of the CVB Class carriers were completed in time to take part in war operations, the effectiveness of armored flight decks against Kamikaze attacks was demonstrated by various carriers attached to the British Pacific Fleet...
The concept went to finding a larger carrier that could support both deck armor and a sufficiently large air group. Unlike the Royal Navy's aircraft carriers, for which the armored deck was part of the ship structure, the Midway class retained their "strength deck" at the hangar deck level and the armored flight deck was part of the superstructure. The weight-savings needed to armor the flight deck were achieved by removing the planned cruiser-caliber battery of 8-inch (203 mm) guns and reducing the 5-inch antiaircraft battery from dual to single mounts. They would be the last USN carriers to be so designed; the size of the Forrestal class supercarriers would require the strength deck to be located at flight deck level.
The resulting carriers were very large, with the ability to accommodate more planes than any other carrier in the U.S. fleet (30–40 more aircraft than the Essex class). In their original configuration, the Midway class ships had an airwing of almost 130 aircraft. Unfortunately, it was soon realized that the coordination of so many planes was beyond the effective command and control ability of one ship.