World War II Database

Contributor: Bob Bryant

Aircraft carriers played a large part in World War II's decisive victories at sea. These victories, in turn, created the essential conditions for decisive victories on land. Early in the war, aircraft carriers bypassed battleships to become the capital ships around which navies centered their fleets for major offensive operations. The relative number of combat-ready fleet and light carriers (the "fast carriers") significantly affected each navy's capabilities, plans, and success in battle. Damage to carriers from various causes, along with routine overhauls and refittings, reduced the number available for operations. Over the course of the war, the fast carriers afloat were operational, on average, 81% of the time. This percentage ranged from 100% to as low as 47% at any given time. Escort carriers also performed vital, war-winning functions and were, on average, operational 83% of their time afloat.

This article examines the principal causes for damage and sinkings of aircraft carriers that made them retire from battle immediately or shortly thereafter in order to undergo repairs and thereby be unavailable for immediate operations. Causes for being non-operational are presented by theater (Atlantic, Pacific), navy (United States, Royal UK, Imperial Japanese), carrier type (fleet, light, escort), and year that damage was sustained. Several carriers lost operational time on at least five separate occasions due to damage. Their lost-time damage histories are also presented.

1. Lost Operational Time

Two hundred fleet, light, and escort carriers were afloat for some period between September1939 and August 1945. One hundred ninety-six of theses were operational at some point of the conflict. Another four were completed too late to see action.

On average, damage kept fleet and light carriers non-operational about 12% of the time and escort carriers non-operational about 5% of the time. Time taken for overhauls and refitting also reduced carriers' operational time.

2. Summary of Causes For Damage That Resulted in Lost Operational Time

There were at least 229 incidents for which damage was sustained by carriers from enemy weapon systems or causes such as extreme weather (storms, typhoons), collisions, aircraft landing accidents, etc. that resulted in lost operational time. Forty-one of these damage incidents resulted in a carrier sinking. Fourteen incidents of damage involved more than one cause. For example, a carrier may have been damaged by both bombs and aerial torpedoes during a single attack. Taking such multiple causes for the 229 "damage incidents" into account, the number of "damage involvements" due to the various causes totaled 243. Consequently, the total for percentages of damage involvements may equal more than 100% of damage incidents. The percentages shown in the tables below indicate the frequency that a given cause was involved in the 229 incidents of damage/sinkings.

Enemy bombs were the leading cause of lost operational time for aircraft carriers during the war. They were involved in 25% of the 229 damage incidents. In addition, bombs were involved in sinking 44% of carriers sunk. The second largest cause for carriers' lost operational time was attacks by Japan's Special Attack Units, i.e., suicide planes that later became known as kamikazes. Although introduced only in the last year of the war, kamikazes were involved in 19% of the total damage incidents. They were less effective for inflicting sufficient damage to sink carriers, however, and were involved in only 7% of carrier sinkings. Torpedoes launched by submarines and by aircraft were both involved in sinking more carriers than kamikazes, even during the final year of the war after kamikazes had been introduced. Torpedoes were also more efficient in sinking carriers as indicated by the higher percentage of damage involvements that resulted in sinking (59% when submarine-launched and 64% when aircraft-launched. The percentage of damage involvements resulting in sinkings also indicates that surface weapons were more efficient in sinking carriers than aerial-delivered weapons even though aerial weapons resulted in more carriers sunk. Causes other than weapon systems were responsible for 39% of lost time incidents, but accounted for only one carrier sank, an escort carrier.

3. Causes of Carrier Damage by Theater

The leading causes for lost-time damage and for sinkings were significantly different for the Atlantic Theater compared to the Pacific Theater. A total of 196 aircraft carriers were operational at some time during World War II. Eighty-five carriers saw action in the Atlantic Theater and 173 in the Pacific Theater with 62 of these carriers seeing action in both theaters at one time or another. There were a total of 53 lost-time damage incidents and 8 carrier sinkings in the Atlantic compared to 176 incidents and 33 sinkings in the Pacific. Multiple causes for damage were involved in 14 incidents in the Pacific, making involvements there total 190.

Atlantic Theater.

Torpedoes. Torpedoes from submarines were the most effective weapons for damaging carriers in the Atlantic Theater. German U-boats plied waters from the Arctic Ocean to the South Atlantic, including the Mediterranean Sea and Gulf of Mexico, attacking merchant transports carrying war-sustaining supplies to the UK, Russia, Malta, and North Africa. U-boats also attacked the carriers that were escorting the convoys or otherwise patrolling the sea-lanes. These attacks caused damage to carriers on eight occasions, six of which resulted in sinkings. The first carrier sunk during the war (HMS Courageous) was hit by a submarine torpedo in the North Atlantic about two weeks after the war in Europe began. In total, 15% of incidents involving damage to carriers in the Atlantic involved submarine torpedoes.

Bombs. Bombs from German and Italian aircraft rained down on transports and carriers running the gauntlet from Gibraltar to supply Malta. These attacks damaged carriers on six occasions but sank none. Damage was frequently extensive, and resulted in considerable lost operational time as these carriers typically sailed to the US Navy yards for repair. Damage may have been even more extensive had the Royal Navy's carrier decks not been armored. In total, bombs were involved in 11% of damage incidents.

Other Weapon Systems. Only one carrier in the Atlantic Theater (HMS Glorious) was damaged and sunk by warship gunfire. This occurred during the UK evacuation from Norway. Only one carrier was damaged by aerial torpedoes (HMS Indomitable), which occurred during the Allied invasion of Sicily. Another carrier was damaged by hitting an enemy mine off the English coast (HMS Slinger).

Other Causes of Damage. The most frequent causes for carrier damage in the Atlantic did not involve weapon systems. There were 16 incidents of collisions between carriers and friendly warships and another 10 incidents of damage due to extreme weather conditions. Other damage to carriers in the Atlantic resulted from aircraft accidents during landings, groundings, and mechanical failures. One mechanical failure (HMS Dasher), still not totally understood, resulted in an internal explosion and sinking at anchor on the River Clyde, Scotland. Overall, causes other than weapon systems accounted for about two-thirds of damage incidents in the Atlantic Theater compared to one-third for weapon systems.

Pacific Theater.

Twice as many carriers operated in the Pacific Theater compared to the Atlantic Theater. Over three times as many were involved in lost-time damage incidents and four times as many were sunk.

Bombs. In the Pacific Theater, bombs were involved in greatest number of carrier damage incidents and were involved in over half of carrier sinkings. As Japan's conquests expanded rapidly during the opening months of the Pacific War, her land-based naval aircraft bombed and sank USS Langley near Java. Bombs from carrier-based aircraft of Japan's KidM Butai sank the HMS Hermes during the Indian Ocean Raid. During the major carrier battles of 1942, carrier aircraft bombs damaged the fleet carriers ShMkaku and USS Yorktown at the Battle of the Coral Sea, an early turning point in the Pacific War. Bombs from USN carrier dive-bombers sank all four of Japan's fleet carriers engaged at the Battle of Midway (Akagi, Kagi, SMryk, Hiryk), another major turning point. During the struggle for Guadalcanal, the third major turning point in the Pacific War, carrier aircraft bombs damaged USS Enterprise and IJN ShMkaku at the Battle of the Eastern Solomons and damaged those same carriers again, along with IJN ZuihM, at the Battle of Santa Cruz Islands. In addition, attacks involving bombs and aerial torpedoes together sank USS Lexington and IJN ShMhM at Coral Sea, IJN RykjM at the Eastern Solomons, and USS Hornet at Santa Cruz Islands. When major carrier battles resumed two years later in 1944, bombs were involved in damaging or sinking five IJN carriers (Zuikaku, Jun'yM, HiyM, Chiyoda, RykhM) during the Battle of the Philippine Sea. At the Battle off Cape Enga�o during the Allied invasion of the Philippines at Leyte Gulf, an additional three IJN carriers (Zuikaku, Chitose, ZuihM) were sunk by bombs and torpedoes and another (Chiyoda) by bombs and cruiser gunfire. USS Princeton was also sunk by bombs during this invasion. During the remainder of the war, carrier aircraft raids on Japan's home islands by bombs and rockets damaged additional IJN carriers. In total, bombs were involved in 52 incidents causing lost-time damage to carriers in the Pacific Theater, 30% of the total. Eighteen of these attacks resulted in carrier sinkings.

Kamikazes. Starting with their defense of the Philippines in 1944, Japan began using Special Attack Units, aka kamikaze suicide planes, to attack Allied warships. Although they were only employed in the last year of the war, attacks involving kamikazes accounted for 25% of the lost-time damage incidents for aircraft carriers in the Pacific Theater. Some of these kamikaze attacks were combined with the bombing and launching of aerial torpedoes by accompanying aircraft and with warship gunfire. Although kamikazes were involved in 44 lost-time damage incidents, they sank only 3 carriers, all USN CVEs (St. Lo, Ommaney Bay, Bismarck Sea).

Submarine Torpedoes. Submarine-launched torpedoes were involved in 21 (12%) lost-time incidents in the Pacific Theater, about the same percentage as in the Atlantic Theater. Eleven carrier sinkings in the Pacific involved submarine torpedoes. American submariners were plagued by having defective torpedoes for the first 21 months of the Pacific War. Nonetheless, with less than 2% of US naval personnel, American submariners accounted for 55% of Japan's maritime losses, including involvement in sinking eight carriers.

Aerial Torpedoes. Torpedoes launched from aircraft were involved in 13 incidents damaging carriers and in nine incidents sinking them. Most of these successful attacks included bombs as well. USS Yorktown was sunk at the Battle of Midway by a combination of aerial and submarine torpedoes. (Aerial torpedoes might have contributed to damage and sinkings of the four IJN carriers at Midway if it had been possible for the USN attack to involve coordinated use of its torpedo bombers along with dive-bombers and fighters.)

Warship Gunfire. Escort carriers were not intended to participate in toe-to-toe navel gunfights. However, poor communication and questionable USN command decisions during the invasion of the Philippines at Leyte Gulf placed several of these relatively small, thin-skinned carriers squarely before a powerful Japanese fleet. Eighteen-inch shellfire from battleship Yamato, the largest battleship ever built, along with 8-inch salvos from IJN cruisers, contributed to sinking the escort carrier USS Gambier Bay at the Battle Off Samar. Warship gunfire also damaged USS Fenshaw Bay, and the combination of gunfire and kamikaze attacks damaged two additional US escort carriers during the same battle (USS Kalinin Bay, White Plains). The same day, bombs and cruiser gunfire sank the light carrier Chiyoda at the Battle off Cape Enga�o, also part of the invasion of Leyte Gulf. In total, warship gunfire was involved in five lost-time incidents including two sinkings in the Pacific. Gunfire alone sank only one carrier in the Pacific Theater (USS Gambier Bay), as was also the case in the Atlantic Theater (HMS Glorious).

Mines. Magnetic mines dropped by the Allies during July 1945 in Japan's Inland Sea resulted in only two damage incidents to carriers, both to KaiyM, which was ultimately knocked out of action by bombs and rockets.

Other Causes of Damage. Weather conditions, collisions, aircraft accidents, etc., in the Pacific Theater played a smaller percentage part in damaging aircraft carriers than in the Atlantic Theater. In total, damage from other than weapon systems accounted for 30% of lost-time incidents in the Pacific compared to 68% in the Atlantic.

4. Causes of Carrier Damage By Navy.

Aircraft carriers of the Imperial Japanese Navy had been at war with China since 1932 when carrier aircraft from HMshM and Kaga supported Japanese troops during the "Shanghai Incident." War began for the UK in September 1939, more than two years before the US formally entered the war in December 1941. Although entering the war later than the other combatants, the United States Navy (USN) ultimately had more carriers afloat during the war than the combined total for the Royal Navy (RN) and the Imperial Japanese Navy (IJN), and USN carriers experienced a greater number of damage incidents resulting in lost-operational time.

Axis bombs and kamikazes were the principal weapon systems causing Allied lost-time carrier incidents, together being involved in 39% of them. Extreme weather and collisions with friendly ships were the causes for almost as many damage incidents for the Allies, being involved in 33% of them. For IJN, Allied bombs and submarine torpedoes were involved for 92% of lost-time incidents, and causes other than weapon systems were involved in only 4% of them. (These values may reflect under-reporting of IJN incidents involving causes other than weapon systems.)

Sinking Allied carriers principally involved submarine torpedoes and bombs. For IJN carriers, all were sunk in attacks involving bombs, submarine torpedoes, and aerial torpedoes.

Royal Navy (RN).

The UK had 63 carriers operational during the war. They were involved in a total of 59 lost-time damage incidents, 24 of which involved enemy weapon systems and 35 that involved other causes, specifically collisions with friendly ships, extreme weather conditions, accidental groundings, aircraft accidents during takeoffs and landings, and mechanical failures aboard carriers.

Eight RN carriers were sunk during the war, five of them by German U-boat torpedoes in the Atlantic Ocean and Mediterranean Sea. Another was sunk by battleship gunfire in the North Sea during the opening weeks of the European war (HMS Glorious) with the loss of 1,207 men, the largest RN loss of the war. Another was sunk by bombs from Japanese carrier aircraft in the opening months of the Pacific War (HMS Hermes) with the loss of 306 men. HMS Dasher sank after an internal explosion while at anchor in home waters that took 379 men down with her. In response to the loss of Dasher, the RN began routinely modifying CVEs constructed in the US to meet greater fueling-related safety standards before releasing them for operations. This may have reduced future casualties aboard UK CVEs, but it also increased the time they remained non-operational.

Imperial Japanese Navy (IJN).

Japan had a total of 25 operational carriers during the war. These were reportedly involved in 53 lost-time incidents, almost all of which were due to enemy weapon systems. Other causes included one involving mechanical failure and another involving an accidental grounding. Aerial weapon systems including bombs, rockets, and aerial torpedoes were involved in 39 lost-time damage incidents for IJN carriers. Submarine torpedoes were involved in 16 such incidents.

By the end of the Pacific War, 21 of Japan's 25 aircraft carriers had been sunk and another four rendered inoperable and serving only as anti-aircraft platforms for the defense of the home islands. Seven of these carriers were sunk by bombs alone, five by bombs in combination with aerial torpedoes, and one by bombs in combination with cruiser gunfire. Eight IJN carriers were sunk by submarine torpedoes. No IJN carriers were sunk from other causes. Japanese losses for the six major carrier battles of the war were over 20,000 men and 1,400 aircraft.

Initial Lost-Time Incidents (Dec 1941- Apr 1942). Japan sustained no lost-time damage to operational carriers from enemy attacks during the first five months of the Pacific War. During that period, her powerful Mobile Fleet (KidM Butai) dominated Pacific and Indian Ocean waters. A 500 lbs. bomb hit from a B-25 Mitchell during the Doolittle Raid of April 1942 did delay conversion of RykhM from a submarine tender to a light carrier. Also, the accidental grounding of Kaga in February of that year prevented her from participating in Japan's Indian Ocean Raid in April.

Early Carrier Battles (May-Oct 1942). With the Battle of the Coral Sea and the damage to ShMkaku, Allied attacks began inflicting severe damage and losses on IJN carriers, aircrews, and aircraft. Four of the six carriers of Japan's powerful Kido Butai that were committed to the failed invasion of Midway (Akagi, Kaga, Hiryk, Soryu) were sunk by bombs from carrier-launched USN dive-bombers. A mechanical failure aboard Hiyo forced her to withdraw from action off Guadalcanal in October 1942. The four major carrier battles of 1942 (Coral Sea, Midway, Eastern Solomons, and Santa Cruz Islands) cost Japan a total of six carriers, over 4,800 combat-experienced men, and over 500 aircraft. The last two of these carrier battles were part of the six month IJN campaign to retake Guadalcanal in which almost 1,900 pilots and 892 planes were lost. IJN was unable to fully recover from this period of attrition for ship, aircraft, and human resources. Although Japan still had three operational carriers available in the Pacific Theater at the end of October 1942 following the Guadalcanal battles, compared to no operational carriers in the Pacific for the Allies, IJN chose not to undertake offensive carrier operations at that time. Nor did IJN do so for the next two years, during which time the Allies brought an additional eighteen fast carriers to the Pacific.

Battle of the Philippine Sea (June 1944). The Mariana Islands were a key part of Japan's inner defense perimeter as well as home to many Japanese civilians. Unless stopped, Allied aircraft operating from the Marianas could bomb Japan's home islands. IJN responded to the Allies' move against the Marianas in June 1944 by sending a fleet including nine fleet and light aircraft carriers to oppose a US fleet including 15 such carriers. The result was in the largest carrier-to-carrier battle in history. Submarine torpedoes sank two IJN carriers enroute to the battle zone (TaihM, ShMkaku). Bombs damaged five others, including one sunk by both bombs and aerial torpedoes (HiyM). Total Japanese losses for the battle are estimated at about 3,000 men and 600 aircraft, including both carrier-launched and land-based planes.

Battles of Leyte Gulf (Oct 1944). Following the losses during the Philippine Sea battle, IJN no longer had an effective carrier combat capability. In addition, two IJN escort carriers were sunk by submarine torpedoes in the following months (TaiyM, Un'yM). When the Allies launched their invasion of the Philippine Islands at Leyte Gulf, IJN countered with a powerful fleet of battleships, cruisers, and destroyers to disrupt the landing. They used their carriers, however, only as a decoy fleet to lure the USN Third Fleet away from IJN's intended target area. US carrier aircraft and warships caught up with this decoy fleet off Cape Enga�o and sank three IJN carriers with bombs and aerial torpedoes (Chitose, Zuikaku, ZuihM) and another with bombs and cruiser gunfire (Chiyoda). Total Japanese losses for the four naval battles comprising the overall resistance to the Leyte Gulf invasion are estimated at 12,500 casualties and 300 carrier and land-based aircraft.

Further IJN Carrier Losses (Nov-Dec 1944). USN submarines, finally with reliable torpedoes and in large numbers, successfully attacked IJN carriers that were now reduced primarily to transport missions. Submarine torpedoes sank three IJN carriers (Shinyo, Shinano, Unryk) and damaged a fourth (Jun'yM) in the shrinking ocean areas in which IJN continued to operate. These attacks cost Japan about 4,000 men and 100 aircraft.

Defense of Home Islands (1945). Unable to initiate credible naval attacks, IJN carriers remained in Japan's home waters only to become targets of sustained Allied bombing raids. Bombs and aerial-launched rocket attacks, mostly at targets in Japan's Inland Sea, resulted in 15 lost-time damage incidents to 5 carriers including the sinking Amagi and abandonment of KaiyM. Ultimately, the carriers that were not sunk were stripped of their aircraft and aircrews and served only as anti-aircraft platforms for the remainder of the war.

United States Navy (USN)

The United States had 108 operational carriers during the war. USN carriers experienced 117 lost-time incidents. Enemy weapon systems were involved in 72 such incidents and other causes involved in 52. Although kamikazes were used only during the final year of the war, they were involved in the largest number of lost-time incidents for USN carriers (37), twice the number as for bombs alone (18). The USN lost 12 carriers during the war. Allied losses, mostly American, for the six major carrier battles of the war were about 4,400 men and less than 650 aircraft.

Initial Lost-Time Incidents (Dec 1941-Apr 1942). During the five months following the attack on Pearl Harbor, Japan had more than twice as many operational carriers in the Pacific Theater as the US. Rather than seeking a direct confrontation with the enemy's more powerful fleets, the USN engaged its carriers in hit-and-run tactics on enemy positions. These raids resulted in no lost-time incidents, but a USN carrier was damaged by an IJN submarine torpedo off Hawaii (USS Saratoga) and another carrier sunk by bombs from Japanese aircraft near Java in the Netherlands East Indies (USS Langley).

Early Carrier Battles (May-Oct 1942). Faced with Japanese naval actions that might isolate Australia, and armed with excellent intelligence about Japanese plans, the USN committed its carriers to battles at the Coral Sea and Midway where it won strategic, tide-turning victories. These came at the cost of losing two fleet carriers (USS Lexington, Yorktown) to bombs, aerial torpedoes, and submarine torpedoes. The battles of attrition on land, in the air, and on the sea for control of Guadalcanal beginning in August 1942 cost the US another two carriers sunk (USS Wasp, Hornet) and two others damaged (USS Enterprise, Saratoga), again by bombs, aerial torpedoes, and submarine torpedoes. Consequently, for a two-week period at the end of October 1942, USN had no operational carriers in the Pacific Theater. All told, the four major carrier battles of 1942, along with the sinking of the Wasp, cost the Allies about 1,500 men and 350 aircraft in comparison to considerably greater Japanese losses. This war of attrition favored the Allies, which could make good its losses while the Japanese could not. Strategically important, the Allies held Guadalcanal and the vital airfield from which they now threatened Japanese positions in the upper Solomon Islands, New Guinea, and even the major IJN base at Rabaul.

Invasion of North Africa (Nov 1942). Even as the battle for Guadalcanal raged in the Pacific Theater, the Allies invaded of North Africa. Two of the CVEs providing air cover and transporting aircraft for the invasion suffered damage from extreme North Atlantic weather. A third suffered bomb damage from its own aircraft during a launching accident. American invasion forces were launched from ports thousands of miles away from the landing zones, the longest such amphibious assault ever attempted. Even so, and even with German U-boats active in the Atlantic, no damage from enemy action resulted in lost operational time for USN carriers.

Drive Across the Central Pacific (Nov 1943-Nov 1944. Strengthened by more than a dozen newly commissioned carriers of all types, the USN undertook invasions of the Gilbert and Marshall Islands. Japanese aerial torpedoes damaged a light carrier (USS Independence) and an Essex class fleet carrier (Lexington) near Tarawa and Kwajalein respectively. IJN submarine torpedoes sank an escort carrier (Liscome Bay), also near Kwajalein. Five ship collisions and an aircraft accident involving a crash landing on deck of the Sangamon enroute to the battle zone also caused lost operational time. USS Intrepid was damaged by aerial torpedoes during a raid on the IJN base at Truk in the Caroline Islands. The only damage during the invasion of the Mariana Islands was to the CVE USS Fenshaw Bay, which took a bomb during the landings on Saipan. Remarkably, little lost-time damage was inflicted upon USN carriers during the Marianas campaign, which included the major carrier-to-carrier battle in the Philippine Sea

CVE's in the Atlantic (May-June 1944). The USN's highly effective cadre of hunter-killer CVEs engaged in anti-submarine warfare in the Atlantic was not without casualties. USS Block Island was sunk by U-boat torpedoes off the Canary Island. She was the only USN carrier sunk in the Atlantic Theater during the war. USS Mission Bay, then deployed for aircraft transport, lost operational time after colliding with a dredge in New York Harbor.

Invasion of Leyte Island (Oct-Dec 1944). USN carriers experienced substantial numbers of lost-time damage incidents while invading and securing Leyte Island in the Philippines. Carriers USS Hancock and Franklin took bomb hits during raids on Formosa that were preliminary to the invasion. CVE Sangamon and CVL Princeton also took bomb hits, the latter being sunk east of Luzon Island. Highly notable was the damage done to a small group of CVEs and their escorting destroyers and destroyer escorts known as "Taffy 3" that unexpectedly came toe-to-toe with a powerful Japanese battle fleet enroute to Leyte Gulf intending to disrupt the Allied invasion there. The extraordinarily brave and aggressive action by the USN carriers and their escorts caused the Japanese fleet to withdraw, but not before USS Gambier Bay was fatally hit with 8-in shellfire from IJN cruisers and, possibly, also with 18-inch shellfire from IJN super-battleship Yamato. USS Fanshaw Bay, Kalinin Bay, and White Plains were also hit with warship gunfire. Further, it was during this desperate Battle Off Sumar that Japan's Special Attack Units, later known as kamikazes, made their initial attacks. Kamikaze hits damaged a total of four USN CVE during this battle, sinking USS St. Lo. Kamikazes damaged another ten USN carriers during the invasion of Leyte.

Invasion of Mindoro and Luzon Islands (Dec 1944-Jan 1945). Kamikazes continued to inflict serious damage to carriers for the rest of the war. Eight carriers were damaged by kamikazes during the invasions of Mindoro and Luzon Islands in the Philippines. These included CV USS Ticonderoga that was hit by two kamikazes with the loss of 143 men and CVE Ommaney Bay, which sank with a loss of 95 men. Nine carriers were damaged when poor weather reporting and questionable command decisions took US Task Force 38 directly into "Typhoon Cobra". Crash landings were involved in two incidents that killed at least 50 men. Overall, the invasions of the Philippines, including on Leyte, involved a total of 47 lost-time damage incidents.

Invasion of Iwo Jima (Feb-Mar 1945). Kamikazes were involved in four of the five lost-time incidents for carriers during the invasion of Iwo Jima. USS Saratoga was hit both by kamikazes and by bombs from Japanese aircraft accompanying the suicide planes, killing 123 men. USS Bismarck Sea was sunk with a loss of 318 men. Kamikazes only needed fuel for a one-way trip and could strike from long distances. The USS Randolph was damaged while anchored in the US naval base at Ulithi in the Caroline Islands, with the loss of 25 dead, by a kamikaze that flew over 1,400 nautical miles from Kyushu, Japan. The other lost-time incident during the Invasion of Iwo Jima was due to a collision of a carrier with an oiler.

Invasion of Okinawa (Mar-July 1945). The invasion of Okinawa and related raids resulted in 37 lost-time incidents. Ten of these were due to extreme weather, almost all from "Typhoon Connie". Nine were due to kamikaze attacks, including the attack on USS Bunker Hill that was hit twice resulting in the loss of 389 men. Another kamikaze attack on USS Hancock killed 62. Six incidents involved aircraft accidents. Five involved bombs, including the attacks with armor-piercing 550 lbs. bombs on USS Franklin and Wasp that together killed 826 men. Collisions, friendly fire, and a refueling accident accounted for another six lost-time incidents.

5. Causes of Damage By Carrier Type.

Almost two-thirds of the carriers operational during the war sustained damage resulting in lost operational time. Almost half of these were damaged more than once. Eighty-five percent of fleet carriers were damaged, proportionately more frequently than other types. Fleet carriers were typically engaged more aggressively in operations and typically operational for longer periods during the war.

Of the 229 damage incidents for carriers that resulted in lost operational time, 94 involved fleet carriers (CVs), 29 involved light carriers (CVLs), and 106 involved escort carriers (CVEs). Of the 41 carriers sunk during the war, 19 were CVs, 7 were CVLs, and 15 were CVEs. All but one carrier (CVE HMS Dasher) were sunk by weapon systems rather than other causes.

Fleet Carriers (CVs). Fleet carriers were the key capital ships of the war and, accordingly, they were principal targets for attack. 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.

Of the 94 incidents of lost-time damage for fleet carriers, 67 involved aerial weapon systems and 15 involved surface weapon systems (14 by submarine torpedoes and 1 by warship gunfire). Non- causes were involved 18 times. For the 19 sinkings, bombs and submarine torpedoes were each involved nine times. Aerial-launched torpedoes were involved five times and warship gunfire just once.

Light Carriers (CLVs). Light 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 beginning of the war typically reflected the immediate need for fast carriers that took advantage either of readily available ship hulls for conversion to aircraft carriers or reflected the maximum hull size that available commercial shipyards could handle. While these carriers made significant contributions to the war effort, their relatively small size made them operationally inefficient. The principal measure of naval power was the number of fleet carriers a navy could deploy.

Of the 29 lost-time damage incidents for light carriers, bombs were involved 15 times and other weapon systems a total of nine times. Extreme weather conditions were involved six times. There were about half the number of CVLs in the war compared to CVs, but they accounted for only about one-third of the lost-time damage incidents. All CVLs except the one sunk by warship gunfire were sunk by aerial weapon systems.

Escort Carrier (CVEs). Escort carriers were smaller, slower, lightly armored, and typically capable of carrying 20 to 30 operational aircraft. They were not typically included with naval battle fleets, but during the war, they performed every function that the larger carriers did. When Japan began employing Special Attack Units, aka kamikazes, in late 1944, CVEs were perceived to be particularly vulnerable. Their invasion support functions required them to remain off hostile shores for lengthy periods without the speed, maneuverability, and larger defensive screens typically enjoyed by the larger carriers.

Of the 106 damage incidents for escort carriers, 48 involved systems and 61 involved non-weapon systems causes, mostly extreme weather and collisions. Of the 15 CVE sunk, submarine torpedoes were involved in 8, kamikazes were involved in 3, bombs in 2, and gunfire in 1. CVEs were the only carrier type sunk by kamikazes during the war.

6. Causes of Damage By Year.

Of the 229 lost-time damage incidents, 13 occurred against UK carriers engaged in the Atlantic Theater before 1942. Four of these incidents resulted in carriers being sunk. During the first year after the attack on Pearl Harbor, the intense naval war of attrition in the Pacific Theater, which involved four major carrier battles, resulted in increasing the number of worldwide annual lost-time carrier incidents to 40, including 14 sinkings. With USN and IJN operational carrier numbers depleted, 1943 saw annual incidents declining to 18 including only 3 sinkings. The following year, with IJN desperately attempting to maintain an effective defensive perimeter around Japan, and with dramatically increased numbers of Allied carriers then engaged, incidents increased to 88 including 16 sinkings, The sinkings were principally the result of two major carrier battles. Lost-time incidents continued at the high level of 84 in 1945, but IJN's dramatically reduced naval capability limited the number of carriers sunk to only four. Overall, aircraft carriers contributed greatly to making 1942 the pivotal, turning point of the war, 1944 the decisive year, and 1945 one for essentially finishing up, albeit at great cost.

1939-1941. Before the Japanese attack on Pearl Harbor in late 1941 that formally brought the US into World War II, Britain's carriers experienced a variety of lost-time damage incidents. Submarine torpedoes, mechanical failures, gunfire from German battleships, etc. resulted in lost operational time. Most such incidents resulted from bombing by Italian and German land-based aircraft. In addition there was a submarine attack during efforts to sustain British forces in the Mediterranean at Malta. additional lost-time damage incidents occurred off England, off Norway, near Dakar in Africa, and in the Caribbean. Three carriers, all British CVs, were sunk prior to the attack on Pearl Harbor and a forth, a British CVE, was sunk two weeks later. Three of these carriers were sunk by German U-boats and one by German battleship gunfire.

1942. For the first four months of 1942, Japan's powerful carrier force, the KidM Butai, dominated Pacific and Indian Ocean waters. With fewer carriers than the IJN operating in the Pacific Theater, the USN initially limited its response to carrier-launched aircraft raids on Japanese bases. From May through October, however, in response to IJN invasion plans and using significant intelligence breakthroughs to compensate for its lesser naval power, USN initiated four major carrier battles (Coral Sea, Midway, Eastern Solomons, Santa Cruz Islands) that shifted the strategic initiative in the Pacific from Japan to the Allies. After the two carrier battles off Guadalcanal, the percentage of aircraft carriers afloat that were in fact available for combat operations was typically less than 70%. During the Guadalcanal campaign, that percentage fell below 50%. In the Atlantic, Axis submarines and land-based bombers continued to attack Allied merchant shipping and its carrier escorts. Of the 35 lost-time damage incidents suffered in 1942 by all navy's carriers worldwide, 20 involved bombs, eight involved submarine torpedoes, and five involved aerial torpedoes. Similarly, of the 14 carrier sinkings, ten involved bombs, four involved submarine torpedoes, and five involved aerial torpedoes. No other weapon systems or other causes resulted in carriers sinking.

1943. With the Allies and Japan recovering from their naval losses of the previous year, and with fewer successful attacks on carriers in the Atlantic, extreme weather, collisions, and other causes resulted in as many lost-time damage incidents as enemy weapon systems. Worldwide, submarine torpedoes were involved in six damage incidents and aerial torpedoes in another three. Only two carriers were sunk in the Pacific during 1943, one USN and one IJN, both by submarine torpedoes. The only carrier sunk in the Atlantic that year was due to an explosion resulting from a mechanical failure on a CVE at anchor.

1944. Carrier activity increased in 1944 as the Allies drove across the Pacific to invade the Marianas and up from Indonesia and the Solomon Islands to meet at the Palau and then the Philippines Islands. Two major carrier battles were fought. Japan introduced the use of Special Attack Units, and kamikazes were involved in 16 lost-time damage incidents, more than any other weapon system. Nonetheless, kamikaze were involved in sinking only one carrier. In the Atlantic, most of the lost-time incidents did not involve weapon systems. A U-boat torpedo caused the only USN carrier lost in the Atlantic during the War. Worldwide, aerial weapon systems were involved in 36 lost-time damage incidents, surface weapon systems in 17, and all other causes in 25. Submarine torpedoes were involved in eight of the 16 sinkings. Bombs and aerial torpedoes were involved six and four times respectively. Warship gunfire was involved in 2 sinkings.

1945. The final year of the war in the Atlantic Theater saw less naval activity as the conflict there shifted almost entirely to land warfare. Accordingly, the Royal Navy shifted most of its carriers to the Pacific. There were only four lost-time carrier damage incidents in the Atlantic, one resulting from a submarine torpedo and three from other than weapon systems. In the Pacific, Japan relied heavily upon Special Attack Units to slow the Allied advance. Kamikazes accounted for an increasing percentage of damage to Allied carriers and sank two. Bombs continued to be involved in a high number of lost-time damage incidents and were involved in sinking two. RN carriers with armored decks sustained less lost time and fewer casualties than the US carriers, whose decks were not armored.

7. Causes of Carrier Damage For Specific Aircraft Carriers

Fourteen carriers sustained damage on at least four occasions that resulted in lost operational time. HMS Illustrious and Indomitable, along with USS Enterprise and Saratoga, were afloat for almost the entirety of the war, surviving all attacks, which explains in part their relatively large number of lost-time damage incidents. The Japanese CVE KaiyM, on the other hand, suffered through repeated air attacks during a relatively short period of 1945 while confined to Japan's vulnerable and mined Inland Sea.

Six carriers lost operational time on at least five separate occasions due to damage. Their lost-time damage incident histories are listed in the table below. Of these carriers, only the CVE IJN KaiyM was technically "sunk", damaged beyond use as an aircraft carrier and ultimately abandoned at anchor in Japan's Inland Sea after repeated bomb damage.