text: Post-World War II The years following World War II brought many revolutionary new technologies to naval aviation, most notably the helicopter and the jet fighter, and with this a complete rethinking of its strategies and ships' tasks. Although several of the latest Commencement Bay-class CVE were deployed as floating airfields during the Korean War, the main reasons for the development of the escort carrier had disappeared or could be dealt with better by newer weapons. The emergence of the helicopter meant that helicopter-deck equipped frigates could now take over the CVE's role in a convoy while also performing their usual role as submarine hunters. Ship-mounted guided missile launchers took over much of the aircraft protection role, and in-flight refueling eliminated the need for floating stopover points for transport or patrol aircraft. Consequently, after the Commencement Bay class, no new escort carriers were designed, and with every downsizing of the navy, the CVEs were the first to be mothballed.
  Several escort carriers were pressed back into service during the first years of the Vietnam War because of their ability to carry large numbers of aircraft. Redesignated AKV (air transport auxiliary), they were manned by a civilian crew and used to ferry whole aircraft and spare parts from the U.S. to Army, Air Force and Marine bases in South Vietnam. However, CVEs were useful in this role only for a limited period. Once all major aircraft were equipped with refueling probes, it became much easier to fly the aircraft directly to its base instead of shipping it.
  The last chapter in the history of escort carriers consisted of two conversions: as an experiment,  was converted from an aircraft carrier into a pure helicopter carrier (CVHA-1) and used by the Marine Corps to carry assault helicopters for the first wave of amphibious warfare operations. Later, Thetis Bay became a full amphibious assault ship (LHP-6). Although in service only from 1955 (the year of her conversion) to 1964, the experience gained in her training exercises greatly influenced the design of today's amphibious assault ships.