Battle of the Philippine Sea
The Battle of the Philippine Sea was a major naval battle of World War II on 19–20 June 1944 that eliminated the Imperial Japanese Navy's ability to conduct large-scale carrier actions. It took place during the United States' amphibious invasion of the Mariana Islands during the Pacific War. The battle was the last of five major "carrier-versus-carrier" engagements between American and Japanese naval forces,[3][N 1] and pitted elements of the United States Navy's Fifth Fleet against ships and aircraft of the Imperial Japanese Navy's Mobile Fleet and nearby island garrisons. This was the largest carrier-to-carrier battle in history, involving 24 aircraft carriers, deploying roughly 1,350 carrier-based aircraft.[4]
The aerial part of the battle was nicknamed the Great Marianas Turkey Shoot by American aviators for the severely disproportional loss ratio inflicted upon Japanese aircraft by American pilots and anti-aircraft gunners.[5] During a debriefing after the first two air battles, a pilot from USS Lexington remarked "Why, hell, it was just like an old-time turkey shoot down home!"[6] The outcome is generally attributed to a wealth of highly trained American pilots with superior tactics and numerical superiority, and new anti-aircraft ship defensive technology (including the top-secret anti-aircraft proximity fuze), versus the Japanese use of replacement pilots with not enough flight hours in training and little or no combat experience. Furthermore the Japanese defensive plans were directly obtained by the Allies from the plane wreckage of the commander-in-chief of the Imperial Japanese Navy's Combined Fleet, Admiral Mineichi Koga, in March 1944.[7][8][N 2][N 3]
During the course of the battle, American submarines torpedoed and sank two of the largest Japanese fleet carriers taking part in the battle.[9] The American carriers launched a protracted strike, sinking one light carrier and damaging other ships, but most of the American aircraft returning to their carriers ran low on fuel as night fell. Eighty American planes were lost. Although at the time the battle appeared to be a missed opportunity to destroy the Japanese fleet, the Imperial Japanese Navy had lost the bulk of its carrier air strength and would never recover.[2] This battle, along with the Battle of Leyte Gulf four months later, marked the end of Japanese aircraft carrier operations. The few surviving carriers remained mostly in port thereafter.
Background[edit]
Japanese plan for a decisive battle[edit]
From the very start of the conflict in December 1941, the Japanese war plan had been to inflict such severe and painful losses on the US military that its public would become war weary and the American government would be convinced to sue for peace and allow Japan to keep its conquests.[10]
Admiral Isoroku Yamamoto had grown wary of this strategy, but he was killed in Operation Vengeance on 18 April 1943. The following day, Admiral Mineichi Koga succeeded Yamamoto as commander-in-chief of the Combined Fleet, and Koga wanted the Imperial Japanese Navy to engage the American fleet in the "single decisive battle" in early 1944. On 31 March 1944 Koga was killed when his aircraft (a Kawanishi H8K) flew into a typhoon and crashed.[11] Koga's chief of staff, Vice Admiral Shigeru Fukudome, was flying in an accompanying plane and carrying the Z Plan documents, and also crashed. Fukudome survived, but the Z Plan briefcase did not sink with the destroyed aircraft and was recovered by Filipino guerillas who over the next few weeks transported the documents to General Douglas MacArthur's Military Intelligence Service (MIS) in Brisbane, Australia. MIS forwarded the translated Z Plan to Admiral Chester Nimitz in Honolulu, and the Japanese plans were quickly dispatched to the fleet commanders in the Philippine Sea in June.[7][8] A new commander-in-chief of the Combined Fleet, Admiral Soemu Toyoda, was appointed, and he finalized the Japanese plans known as Plan A-Go or Operation A-Go. Operation A-go did not change much from the Z Plan, so the U.S. Navy knew exactly what was going to happen during the upcoming naval battle.[12] The plan was adopted in early June 1944. Within weeks, an opportunity arose to engage the American fleet now detected heading for Saipan.[13]
The Japanese had some advantages they hoped would turn the battle in their favor. Though outnumbered in ships and aircraft, they planned to supplement their carrier airpower with land-based aircraft.[11]
Advantages for the Americans[edit]
Meanwhile, IJN aircrew losses, suffered during earlier carrier battles at Coral Sea, Midway, and the long Solomon Islands campaign of 1942–43, had greatly weakened the Japanese Navy's ability to project force with its carriers.[14] Losses suffered in the Solomons drastically reduced the number of skilled carrier pilots available to fill the carrier air groups. It took nearly a year for the Japanese to reconstitute their groups following the Solomons campaign.[10]
Japan no longer had enough oil tankers to transport the required volume of petroleum from the Dutch East Indies to Japanese refineries. Without adequate supplies of refined residual fuel oil, Japanese aircraft carriers refueled with unrefined Tarakan petroleum in June 1944. This undesalted petroleum damaged boiler tubes, and the unremoved naphtha fraction volatilized the fuel to form explosive atmospheres incompatible with aircraft carrier damage control procedures.[15]
In early 1944 the U.S. fleet continued its advance in a steady progression across the islands of the central Pacific.[16] While U.S. commanders, particularly Admiral Spruance, were concerned about the Japanese trying to attack U.S. transports and newly landed forces, the Japanese objective was actually to engage and defeat the Fast Carrier Task Force in a decisive battle.[17]
Aftermath[edit]
Japanese[edit]
That night, Toyoda ordered Ozawa to withdraw from the Philippine Sea. U.S. forces gave chase, but the battle was over. The four Japanese air strikes involved 373 carrier aircraft, of which 243 were lost and 130 returned to the carriers; many of them were subsequently lost when Taiho and Shōkaku were sunk. After the second day of the battle, losses totaled three carriers, more than 350 carrier aircraft, and around 200 land-based aircraft.
In the five major "carrier-on-carrier" battles, from the Battle of the Coral Sea to the Battle of the Philippine Sea,[N 1] the IJN had lost nine carriers, while the USN had lost four. The aircraft and trained pilots lost at Philippine Sea were an irreplaceable blow to the already outnumbered Japanese fleet air arm. The Japanese had spent the better part of a year (following the Battle of the Santa Cruz Islands) reconstituting their depleted carrier air groups, and the American Fast Carrier Task Force had destroyed 90% of it in two days. The Japanese had only enough pilots left to form the air group for one of their light carriers. As a consequence, during the Battle of Leyte Gulf four months later, they sent out a decoy carrier group with only 108 aircraft, across six carriers (two were hybrid-carriers), that was sacrificed in an attempt to draw the American fleet away from protecting the troops and supplies being landed for the Battle of Leyte.
The Japanese military, which had hidden the extent of their previous losses from the Japanese public, continued this policy. Though the occurrence of the simultaneous Battle of the Philippine Sea and the Battle of Saipan were made known to the public, the extent of the disasters was withheld.[48]
American[edit]
Losses on the U.S. side on the first day were 23 aircraft. The second day's airstrike against the Japanese fleet saw most of the aircraft losses for the U.S.; of the 226 aircraft launched on the strike, 115 returned; 20 were lost to enemy action in the attack, and 80 were lost when they ran out of fuel returning to their carriers and had to ditch into the sea, or crashed attempting to land at night.[49]
Spruance's conservative battle plan for TF 58, while sinking just one light carrier, severely weakened the Japanese naval aviation forces by killing most of the remaining trained pilots and destroying their operational reserves of naval aircraft, a blow that effectively shattered the Japanese naval air arm, from which it never recovered.[50] Without the time or resources to build sufficient aircraft and train new pilots, the surviving Japanese carriers were almost useless in an offensive role, a fact the Japanese acknowledged by using them as sacrificial decoys at Leyte Gulf. With the effective crippling of her best striking arm, Japan chose to rely increasingly on land-based kamikaze suicide aircraft in a last-ditch effort to make the war so costly that the U.S. would offer peace terms better than unconditional surrender.
Spruance was heavily criticized after the battle by many officers, particularly the aviators, for his decision to fight the battle cautiously rather than exploiting his superior forces and intelligence data with a more aggressive posture. By failing to close on the enemy earlier and more forcefully, his critics argue, he squandered an opportunity to destroy the entire Japanese Mobile Fleet. "This is what comes of placing a non-aviator in command over carriers" was the common refrain.[51] Admiral John Towers, a naval aviation pioneer and Deputy Commander-in-Chief Pacific Fleet, demanded that Spruance be relieved.[52] The request was denied by Nimitz. Moreover, Spruance was supported in his decision by Admiral Kelly Turner and Admiral Ernest King, Chief of Naval Operations.[53]
Spruance's caution (in particular, his suspicion of a diversionary force) can be compared with Admiral William Halsey's headlong pursuit of an actual diversionary force at Leyte Gulf four months later. Halsey left the American invasion fleet weakly protected during the Battle off Samar, nearly resulting in a devastating attack on the landing force by Japanese heavy surface units. It was prevented only by the heroic and desperate attack of 5 small American surface ships, which put up such an intense fight that the 23 ship strong Japanese fleet thought they were engaging a much larger force and withdrew. In addition, by focusing on defense first, the carrier forces under Spruance at Philippine Sea suffered no significant harm. This was in contrast to Leyte Gulf when Halsey's carriers were trying to neutralize the enemy airfields and attack the enemy fleet simultaneously, such that a Japanese bomber managed to evade the Combat Air Patrols to fatally cripple the light carrier USS Princeton. Likewise, during the carrier-based air raids, U.S. carriers were in a vulnerable position, and the low visibility coupled with radar confusion let a Japanese bomber slip through and severely damage USS Franklin.[54]
Although the American carrier aircraft strikes caused less destruction to enemy naval vessels than earlier battles, American submarines made up for it by sinking two of the three Japanese fleet carriers, which left Zuikaku as the only remaining operational IJN fleet carrier.
The American F6F Hellcat fighter proved its worth, as its powerful engine generated superior speed, while its heavier armor and firepower made it rugged and deadly. The Japanese on the other hand were still flying the A6M Zero which, though highly maneuverable and revolutionary during the early stages of the Pacific War, was now underpowered, fragile and essentially obsolete by 1944. In addition, the D4Y "Judy", though fast, was also fragile and easily set on fire. The Japanese naval airmen were also inadequately trained. The Japanese training programs could not replace the quality aviators lost during the past two years of the Pacific Campaign. Flying against the well-trained and often veteran U.S. aviators, it was a one-sided contest. The Americans lost fewer than two dozen Hellcats in air-to-air combat. Naval aviation and anti-aircraft fire shot down nearly 480 Japanese aircraft, 346 of those carrier aircraft on 19 June alone.[55]
A very fortunate result of the Battle of the Philippine Sea for the Allies was it greatly benefited General MacArthur's invasion of Biak in Dutch New Guinea which started weeks before the Mariana Islands operations started. The Japanese military had designated Biak as its most important island of defense in the Southwest Pacific theater. 13 June was the original starting date of a massive operation, spearheaded by the battleships Yamato and Musashi, to challenge MacArthur's paltry naval forces, which had no aircraft carriers or battleships and consisted of only a few cruisers and destroyers. On that very same day Yamato and Musashi and their supporting ships received new orders to head north to screen aircraft carriers that were about to begin Operation A-Go. The battleships didn't take part in the Marianas operations other than anti-aircraft duty.[56][57]