The CVB-41 class vessels 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. 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 was 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. 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 air wing 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. While the resulting ships featured excellent protection and unprecedented air wing size, they also had several undesirable characteristics. Internally, the ships were very cramped and crowded. Freeboard was unusually low for such large carriers; in heavy seas, they shipped large amounts of water (only partially mitigated by the fitting of a hurricane bow during the SCB-110/110A upgrades) and corkscrewed in a manner that hampered landing operations. In addition, in contrast with the earlier Lexington, Yorktown and Essex-classes, the beam (width) of the Midway-class carriers meant that they could not pass through the Panama Canal. Although they were intended to augment the US Pacific fleet during World War II, the lead ship of the class, USS Midway (CV-41), was not commissioned until 10 September 1945 (eight days after the Surrender of Japan). None of the class went on war cruises during the Korean War. They were mainly deployed to the Atlantic and Mediterranean. During the 1950s, all three ships underwent the SCB-110 modernization program, which added angled decks, steam catapults, mirror landing systems, and other modifications that allowed them to operate a new breed of large, heavy naval jets. All three of the Midway class made combat deployments in the Vietnam War. Coral Sea deployed to the Gulf of Tonkin six times, Midway deployed on three occasions, and Franklin D. Roosevelt made one combat deployment before returning to the Mediterranean.