The Essex class is a retired class of aircraft carriers of the United States Navy. The 20th century's most numerous class of capital ship, the class consisted of 24 vessels which came in "short-hull" and "long-hull" versions. Thirty-two ships were ordered, but as World War II wound down, six were canceled before they were laid down and another two after construction had begun. Fourteen saw combat during World War II; none were lost to enemy action, although a few sustained crippling damage due to aerial attacks. Essex-class carriers were the backbone of the U.S. Navy from mid-1943 through the Korean War, and, with the three carriers added just after the war, continued to be the heart of U.S. naval strength until supercarriers joined the fleet starting in the mid-1950s. Most of the carriers were rebuilt, some more thoroughly than others, with less heavily modified examples serving in anti-submarine roles and more heavily updated ones, able to handle moderate-sized jets, seeing service in the Vietnam War, with the last to be retired, being decommissioned as a training carrier in 1991. Of the 24 ships in the class, four, , , and have been preserved as museum ships.

Overview Because of the Washington Naval Treaty of 1922 and subsequent treaties limiting the sizes of warships, the designs of the American carriers that preceded the Essex-class had to incorporate many trade-offs that made them less than fully satisfactory ships. However, in 1934 Japan and Italy, two of the five signatories to the Washington and later (1930) London Naval Treaties, who were both beginning to pursue colonial ambitions (in China and East Africa, respectively) announced that they were withdrawing from the treaty system to pursue unfettered development of their navies. The other signatories proceeded to enter into another treaty, the Second London Naval Treaty of 1936, which extended the basic provisions of the earlier treaties for another six years, but included an "escalator clause," which allowed for limits on ship size, numbers, and armament to be set aside should any of the signatories of the earlier treaties begin to build ships in violation of those earlier treaties' limits. The net result of this was that, from 1937 onward, a new set of naval arms races, similar to those of the 1890s–1910s, began.

Following the departure of Italy and Japan from the system, the United States Congress, on 17 May 1938, passed the Naval Expansion Act, which authorized construction of new aircraft carriers displacing, in total, up to 40,000 tons. This permitted the building of a third, minimally modified Yorktown-class carrier, the first Hornet (CV-8), which was ordered in 1939. The portion of the new authorization that remained after Hornet was ordered was not sufficient to allow construction of the desired, significantly larger vessel as a follow-up. However, in the summer of 1940 the global situation took a major turn for the worse for the United States' soon-to-be-ally, Great Britain, with the collapse of France and the entry of Italy into the European war, leaving Britain with one fewer naval power as an ally and one more as an enemy. In the wake of these events, and seeing American entry into the war as ever more imminent, the Roosevelt administration took action, ordering, on 3 July 1940, not just one, but three new carriers, with a total tonnage of nearly 60,000 tons over the limit thus far authorized by Congress. This lack of authorization was corrected a couple of weeks later, on 19 July 1940, with passage of the Two-Ocean Navy Act, under which funding and statutory authorization for these carriers (Essex, CV-9; Bonhomme Richard, CV-10 [later commissioned as the second Yorktown]; and Intrepid, CV-11) and eight additional ones, all to the same basic design, was authorized. Subsequently, in several stages, Congress would appropriate funds for the construction of 21 additional Essex-class carriers; however, a shortage of building slips capable of handling ships of this size meant that delivery of the ships was a drawn-out process, and of the additional 21, only three would be completed in time to see active service in World War II, while nine others were completed during or just after the war, but did not see service. Six ships ordered in 1944 were canceled before construction was begun, while two more were canceled, partially complete, and scrapped. The last ship was left incomplete for several years to allow ideas on how to modify the design so that the Essexes could continue to be useful in the years ahead to mature; this ship, Oriskany, was finally completed in 1950.

Because so many ships were ordered, and no standard naming convention had yet been adopted for aircraft carriers, a variety of names were used for these ships and the Independence-class light carriers; the majority of these were the names of battles or of previous U. S. Navy vessels, but a few, according to some sources, were named after people (mainly founding fathers), and one, Shangri-La, after a fictional place cited, jokingly, by President Roosevelt as the launching point for the Doolittle Raid of April 1942.

Design

The design of the Essex-class carriers was based largely on that of the preceding Yorktown class, modified to address specific points of dissatisfaction. Compared to Yorktown, the size of the vessel was increased, with length between perpendiculars increased from 770 to 820 feet, and beam from 83 to 93 feet. Overall depth of the hull increased by only about 2 feet, but the hull was submerged a foot or so lower in the water than that of Yorktown, leaving the flight deck at the same approximate height above the water.Aircraft Carrier CV17, Booklet of General Plans, Image 1. Available at Internet Archive website, https://archive.org/details/cv17bogp1946/page/n1/mode/1up Standard displacement grew from 20,000 to 27,600 tons. The original design for the class called for a complement of 215 officers and 2,171 enlisted men; however, by the end of World War II, most crews were c. 50% larger than that, largely because the addition of vast numbers of guns created a need for greater numbers of ammunition-passers.Friedman, Norman (1983). U. S. Aircraft Carriers: An Illustrated Design History. Annapolis, MD: Naval Institute Press, p. 155. ISBN 9780870217395.

Engine power was increased from 120,000 to 150,000 horsepower over the Yorktowns through the adoption of new, modern boilers and machinery designed for use in Atlanta-class light cruisers, two sets of which were used in each Essex.Friedman, Norman (1983). U. S. Aircraft Carriers: An Illustrated Design History. Annapolis, MD: Naval Institute Press, p. 140. ISBN 9780870217395. The way in which the machinery was arranged differed greatly from the previous class: while the Yorktowns had had all of their boilers grouped into one cluster, ahead of a separate cluster incorporating all of the engines, in the new class boilers and machinery spaces alternated with one another, so that a single torpedo hit that penetrated the defensive system (see below) could not damage all of the boilers or all of the engines at once. Many had wanted to incorporate this modification into the design of the third Yorktown, USS Hornet, but this was not done because rapid completion of that ship was a priority, and redesign would have taken too much time.Friedman, Norman (1983). U. S. Aircraft Carriers: An Illustrated Design History. Annapolis, MD: Naval Institute Press, p. 94. ISBN 9780870217395.U.S.S. Hornet (CV8). Transcript of a 19 January 1939 hearing before the General Board of the Navy, Images 36-37. Included on the National Archives website (catalog.archives.gov) as Microcopy 1493, Roll 21, "Vols. 1-2 (1939), Vols. 1-2 (1940); Jan. 19, 1939 THRU Dec. 19, 1940". National Archives Identifier No. 208199024. Accessed 21 January 2026.

The flight deck was significantly larger than those on the Yorktowns, measuring (on early vessels) 862 feet in length and 108 feet in width, compared to 802 and 86 feet on the earlier ships. The deck was supported by a set of deep truss girders, which extended from the underside of the flight deck down approximately 10 feet into the hangar space. Most of these girders were oriented transversely, parallel to each other and spaced 8 to 20 feet apart, and spanned the entire width of the ship, but a single longitudinal girder ran up the centerline of the rear part of the hangar as well. The girders subdivided the uppermost c. one-third of the hangar volume (the portion above the level of the "clear height" cited in reference volumes) into a series of discrete bays, into each of which a spare airplane, with its wings removed, could be "triced up" out of the way until needed. It was hoped early on that the larger size of the flight deck would allow for a larger number of planes--five squadrons worth (c. 90 aircraft)--to be spotted on deck, in order to deliver, in keeping with long-standing U.S. Navy tactical doctrine, a "deck load strike" of the greatest possible power against an enemy as soon as their location was determined; but even as construction was first getting under way it became clear that, given the increasing size and weight of aircraft (expected to be 50 percent heavier, with significantly larger footprints that would require both greater deck space for parking and longer take-off distances), accommodating so many aircraft on deck would not be feasible. Eventually carriage of four 18-plane squadrons, described as a "logical complement," with provision for operation of a fifth squadron, "with certain handicaps," in an emergency, was set as the goal.Characteristics of New Aircraft Carriers. Transcript of 17 July 1939 hearing before the General Board of the Navy, Image 170. National Archives Identifier No. 208199024. Available at catalog.archives.gov. Accessed 23 August 2026. A few months later this was amended slightly: the number of aircraft that should regularly be operated would remain four 18-plane squadrons, plus as many additional fighters (probably nine) as could be accommodated, and c. 5 utility planes.Aircraft Carrier CV9--Characteristics. Transcript of hearing before the General Board of the Navy, 18 January 1940. National Archives Identifier No. 208199024. Available at catalog.archives.gov. Accessed 23 August 2026.