This article discusses aircraft carrier operations during World War II.
Historical overview Naval historians such as Evan Mawdsley, Richard Overy, and Craig Symonds concluded that World War II's decisive victories on land could not have been won without decisive victories at sea. Naval battles to keep shipping lanes open for combatants' movement of troops, guns, ammunition, tanks, warships, aircraft, raw materials, and food largely determined the outcome of land battles. Without the Allied victory in keeping shipping lanes open during the Battle of the Atlantic, Britain could not have fed her people or withstood Axis offensives in Europe and North Africa. Without Britain's survival and without Allied shipments of food and industrial equipment to the Soviet Union, her military and economic power would likely not have rebounded in time for Soviet soldiers to prevail at Stalingrad and Kursk.
Without victories at sea in the Pacific theater, the Allies could not have mounted amphibious assaults on or maintained land forces on Guadalcanal, New Guinea, Saipan, The Philippines, Iwo Jima, or Okinawa. Allied operations in the Atlantic and Pacific theaters were interconnected because they frequently competed for scarce naval resources for everything from aircraft carriers to transports and landing craft. Effective transport of troops and military supplies between the two war theaters required naval protection for shipping routes around the Cape of Good Hope, through the Suez canal, and through the Panama Canal. In both theaters, maritime dominance enabled combatants to use the sea for their own purposes and deprive its use by adversaries. As naval historian Admiral Herbert Richmond stated, "Sea power did not win the war itself: it enabled the war to be won."
Aircraft carriers played a major role in winning decisive naval battles, supporting key amphibious landings, and keeping critical merchant shipping lanes open for transporting military personnel and their equipment to land battle zones.
Ascendancy of aircraft carriers over battleships It became apparent early in the war that control of the air was prerequisite for successful surface action both on land and at sea. For much of the war, Britain and America fought mainly on the seas, where successful Allied naval operations permitted effective support and reinforcement of troops in North Africa, the Soviet Union, western Europe and the Pacific. These operations also crippled similar efforts by Italy and Japan to sustain the empires they built by conquest. By 1942, aircraft carriers with the striking power provided by hundreds of warplanes delivering bombs and torpedoes to targets hundreds of miles away supplanted battleships with big guns as the principal warships around which navies assembled task forces for major campaigns.
Only the United States, United Kingdom, and Japan made significant use of aircraft carriers during the war. The following table shows the number of each type of carrier the principal combatants operated that had at least one flight deck, was capable of both launching and recovering aircraft at sea, and that was operational sometime between July 1937 and August 1945. The counts include carriers in service before the war began as well as those commissioned during the war.
+ Number of aircraft carriers operated and sunk in , Country Fleet Light Escort MAC Total USA 24 9 78 0 111 Britain 12 8 44 19 83 Japan 13 7 5 0 25 France 1 0 0 0 1 Total 50 24 127 19 220 Total sunk 19 7 15 0 41 Sunk percentage 38% 29% 12% 0% 19%
World War II fleet carriers typically displaced 20,000 to 35,000 tons and could sail at 30 to 35 knots. Japanese and American fleet carriers were typically capable of carrying 50 to 90 aircraft into combat. British carriers were designed with armored decks, a measure that provided significantly greater protection against bombs and kamikazes. The additional weight of the armor, however, reduced their typical carrying capability to 35 to 55 aircraft. Thus their additional defensive measures limited their offensive striking power until Britain introduced a new carrier class late in the war.
Light aircraft carriers were fast enough to keep up with the fleet carriers but their smaller size typically reduced their aircraft load to between 30 and 50. The design of those commissioned immediately after the war began typically reflected the immediate need for fast carriers and took advantage either of having other ship hulls available for conversion to aircraft carriers or the available capacity of commercial shipyards to build them. While these carriers made contributions to the war efforts, their relatively small size made them operationally inefficient. The measure of naval power in the Pacific Theater was the number of fleet carriers a navy had.
Escort carriers were smaller, slower, lightly armored, and carried 20 to 30 aircraft. They were not typically included with naval battle fleets, but before the war was over, escort carriers had performed every function that the larger carriers did.
Merchant aircraft carriers (MACs) transported grain and oil in the holds below the flight deck and carried 3 or 4 aircraft to protect themselves and other ships in convoys in which they traveled. None were used for offensive operations.
Land-based aircraft as well as carrier-launched aircraft fought at sea. In the Atlantic Theater, German and Italian aircraft attacked Allied convoys that were protected by fighter aircraft from Allied airfields as long as convoys were within fighter range. As carriers became available, Allied carrier-launched fighters provided protection in those ocean areas that could not be protected by land-based planes. In the Pacific Theater, Japan's successful expansion was typically achieved by progressively using land-based aircraft to support invasions of new areas that were within striking distance of airbases that they had established on previously conquered areas. For the Allies, land-based aircraft at local airfields contributed significantly to America's defense of Midway Island and Guadalcanal. Naval fighters and bombers that operated from land-based airfields were typically delivered to battle zones by aircraft carriers. In both theaters, carrier-launched aircraft played significant roles in dominating the air, and construction of aircraft carriers received priority.
At the same time that America, Britain, and Japan began emphasizing aircraft carrier construction, they de-emphasized construction of battleships. Before the war, the number of battleships a country operated was universally regarded as the principal indicator of naval power. The Japanese attack on Pearl Harbor sank or damaged eight of America's eighteen battleships. The aircraft carriers were at sea and escaped destruction. Six of the eight were repaired and returned to service and eight new battleships were commissioned during the rest of the war. During the period September 1939 to August 1945, America commissioned ten new battleships while Japan commissioned only two and converted two existing ones to hybrid aircraft carriers. Starting the war with 15 battleships and battlecruisers, the UK commissioned five King George V class battleships but the need for smaller vessels precluded building any more. Germany, Italy, and France together commissioned a total of six. All together, only 23 new battleships were added to combatants' fleets during the war years compared to 55 new fleet and light carriers.
During the entire war, battleship guns sank only a single fleet carrier and a single battleship. In comparison, carrier-launched aircraft damaged, sank, or took part in sinking 19 battleships. Although Japan was first to recognize and exploit the greater effective striking power of aircraft carriers over battleships, she was slow to abandon employment of the latter. She commissioned battleships in 1941 and 1942 that were the largest and most heavily armed ever built. After the losses at the Battle of Midway, however, Japan changed naval tactics and began leaving battleships out of major naval engagements. America began primary reliance upon its aircraft carriers for offensive operations early in the Pacific war out of necessity after the destruction of its Pacific battleship fleet during the Japanese raid on Pearl Harbor.
Functions performed by aircraft carriers
Aircraft carriers were used for a wide variety of combat and combat support functions during the war. These included:
Naval battles, during which carrier aircraft attacked each other and enemy warships, as they did during the Battle of Midway between American and Japanese fleets. Invasions, during which carrier aircraft provided support for amphibious landings and for occupying enemy-held positions by bombing those positions before, during, and after landings; spotting for warship guns, sometimes even controlling the firing; delivering replacement aircraft and aircrews to other carriers and to airfields after successful landings, as during the American invasion of Iwo Jima. Raids, during which carrier aircraft attacked enemy positions to degrade them but without the intention of landing and occupying those positions, as during the Japanese Attack on Pearl Harbor and raid on Ceylon. Anti-shipping missions, during which carrier aircraft blockaded enemy ports or attacked enemy shipping and shipping facilities, as during the Allied attacks around Bodø, Norway. Anti-raider missions, in which carrier aircraft searched for and attacked enemy surface ships engaged in raiding enemy merchant shipping, as during the British sinking of the Bismark. Anti-submarine missions, during which Hunter-killer Groups operating independently from convoys and their Escort Groups searched for and destroyed enemy submarines, during the Battle of the Atlantic. Convoy Escort, carrier aircraft searched for and attacked enemy aircraft and submarines that threatened a convoy's merchant ships. Transport, during which carriers delivered aircraft and aircrews to land bases or other carriers, as (CVE) did for Henderson Field on Guadalcanal and as the "CVE Plane Transport Unit" did during the invasion of Okinawa. Training, during which carriers were dedicated to training pilots and/or conducting operating trials to improve carrier tactics and procedures. IJN , , and spent long periods dedicated to training during the war. Repatriation, during which carriers, after the war, participated in returning military personnel to their home countries, as was done under America's Operation Magic Carpet.
The combatants differed in the functions they emphasized for carrier use, in part as a result of the challenges presented by their principal theater of operations. The table below indicates the percentage of carriers each combatant used for each function. For example, the US Navy operated a total of 33 fleet and light carriers during the war. Seventy-three per cent of these carriers participated in naval battles at one time or another. Eighty-five per cent were involved in support of invasions, etc. Escort carriers, although initially envisioned by many to perform only in support roles, ultimately performed all of the functions that the fleet and light carriers did.
+Percentage of Aircraft Carriers Performing Functions Carriers Naval Battles Invasions Raids Anti-Ship. Anti-Raid. Anti-Sub. Convoy Escort Trans. Training Repat. CV & CVL USN 33 73% 85% 82% 9% 0% 3% 15% 15% 3% 45% RN 20 20% 45% 55% 45% 35% 30% 50% 45% 15% 20% IJN 20 75% 50% 30% 0% 0% 0% 5% 35% 10% 10% CVE USN 78 23% 53% 10% 6% 0% 24% 23% 82% 34% 49% RN 44 0% 27% 27% 18% 0% 30% 61% 82% 18% 23% IJN 5 0% 0% 0% 0% 0% 0% 80% 100% 60% 0%
Aircraft carrier contribution to Allied victory