Preliminaries - The A-Go Plan
In September 1943 Japanese Imperial Headquarters resolved that in the near future the entire strength of their fleet would be deployed against the US Navy in a great decisive battle,and that in this battle the enemy fleet would be destroyed "in one blow." By the Spring of 1944 Japanese commanders had decided that the decisive encounter was imminent, and on 3 May the order for the operation - "A-Go" - was issued.
The A-Go Plan was based on the assumption that when the great battle came about the American fleet would be carrying out an offensive in the Central Pacific and that the Japanese would therefore have the advantage of numerous island air-bases within range of the scene of battle. The Japanese command knew that their forces would suffer from a considerable inferiority in carrier airpower, and they were therefore depending on their own land-based air-power to redress the balance.
On June 15 1944 the initial US landings in the Marianas took place - on the island of Saipan. The Japanese had been hoping and expecting that the American attack would come in the Carolines or the Palaus, to the south of the Marianas, and closer to the main Japanese sources of fuel. Their land-based aircraft had been disposed accordingly - with relatively weak forces in the Marianas.
Thus the great operation began with a setback for Japanese strategic hopes. Another blow to their expectations was that the threat from American submarines restricted Japanese carriers to their anchorage, so that they were unable to conduct proper flight training in the run-up to the battle.
A preliminary US carrier strike in the Marianas on June 11 persuaded Admiral Toyoda, C-in-C of the Combined Fleet, that this was where the next landings would take place, and accordingly Japanese forces began to converge on the Marianas for the decisive battle. Their main groupings made rendezvous on June 16 in the western part of the Philippine Sea and completed refuelling on June 17. By the evening of that day Admiral Ozawa, commanding the Japanese forces, had reasonably accurate intelligence of the composition of the US fleet. A few minutes after midnight 17/18 June, Ozawa - in the tradition of the Japanese Navy - issued a final exhortation to all the ships of his fleet :
"This operation has an immense bearing on the fate of the Empire. It is hoped that all forces will do their utmost and attain results as magnificent as those achieved in the Battle of Tsushima."
The Japanese forces had been sighted by American submarines as early as June 15. By June 16 Admiral Spruance, commanding the US Forces (the Fifth Fleet), was satisfied that a major sea battle was approaching, and made plans accordingly. By the afternoon of June 18 Task Force 58 (the Fast Carrier Task Force under Admiral Mitscher) was concentrated near Saipan ready to meet the Japanese fleet.
More intelligence of the Japanese fleet's movements, from submarines and radio intercepts, came in during June18. Shortly before midnight 18/19 June Admiral Nimitz sent Spruance a message from Pacific Fleet Headquarters indicating that the Japanese flagship was approximately 350 miles to the west-south-west of Task Force 58. Shortly afterwards Mitscher sought Spruance's permission to head west during the night to what - as Mitscher and his staff considered - would be an ideal launch position for an all-out dawn air attack on the enemy force.
However, Spruance refused. Throughout the run-up to the battle he had been concerned that the Japanese would try to draw his main fleet away from the landing area using a diversionary force, and would then make an attack around the flank of the US carrier force - an "end run" - hitting the invasion shipping off Saipan. Such methods were a long-standing part of the Japanese Navy's tactical doctrine .
Spruance was intensely conscious that protection of the invasion shipping was his paramount responsibility, and should take precedence over the destruction of the Japanese fleet. Moreover, the Admiral considered, as he was later to observe, that "if we were doing something so important that we were attracting the enemy to us, we could afford to let him come - and take care of him when he arrived." This was to be in effect what happened.
Mitscher and his staff were aghast at Spruance's decision. Captain Arleigh Burke, The Task Force 58 Chief of Staff, bitterly commented that it "meant that the enemy could attack us at will at dawn the next morning. We could not attack the enemy." The Fifth Fleet Commander was adversely criticised by many naval officers after the battle and continues to be condemned - by some writers - to the present day.
A still common allegation is that Spruance decided as he did because he was not an aviator, and therefore could only have had an inadequate understanding of carrier warfare.
Initial Actions of 19 June
This huge fleet - with nearly 99,000 personnel on board - was disposed in five groups - the four carrier groups and Admiral Lee's Battle Line. First came the three stronger carrier groups in a north-south line abreast, with the centres of the groups 12-15 miles apart. Due west of the middle group of this line steamed Task Group 58.7 - Lee's Battle Line - with the weakest carrier group - Harrill's Task Group 58.4 - sailing within visual distance to the north of it. The carrier groups were each disposed in a circle four miles in diameter (with the carriers in the centre of their respective groups but having plenty of room for safe manoeuvering while under attack), and the Battle Line was arranged in a circle about 6 miles in diameter, with the battleship Indiana as guide at the centre of this circle. The formation covered an area of sea roughly 35 miles by 25 miles.
At 0530 the task force turned north-eastwards, directly into
the wind, and began to launch combat air patrol, anti-submarine
patrols and search missions. At 0619 Spruance ordered
a change of course to WSW, hoping thereby to place the fleet closer
to the as-yet unlocated enemy forces. However, the carriers had to turn
back into the wind whenever they were launching aircraft, and at
10am Task Force 58 was in almost exactly the same position as at dawn.
The A-Go plan called for about 500 aircraft to be available on the land bases in the Marianas. In fact, partly because of the damage inflicted by the American carrier forces in strikes made between 11 June and 18 June, there were a mere 50 or so - all of them based on Guam.
The first attack of the day came at 0550 when a scouting Zero from Guam attacked the picket destroyers of the Battle Line and was shot down.
The next action took place over Guam when Hellcats from the light carrier Belleau Wood, investigating a radar contact, encountered Japanese aircraft taking off from Orote Field. At 0807 more Japanese aircraft were detected by radar, heading towards Guam. These were reinforcements flying in from other Japanese-held islands. Fighters were vectored out to intercept them and there was continuous fighting over and around Guam for nearly an hour. 35 Japanese aircraft were shot down, but others were still taking off from Orote when the Hellcats received a "Hey Rube!" signal (calling them back over the carriers) from the task force flagship. Task Force 58 had detected large numbers of unidentified aircraft approaching from the west. These were the planes of the first attack wave from Ozawa's carriers, 68 or 69 aircraft in all.
At about 1036 the first interception was made by 11 Hellcats from the carrier Essex. As these fighters, led by Lt-Commander C.W. Brewer, were carrying out their attack they were joined by other Hellcats from Bunker Hill, Cowpens and Princeton. In this initial action of the carrier battle at least 25 Japanese aircraft were shot down. Task Force 58 lost only one fighter. This set the pattern for the air-to-air combats of the day.
The Japanese planes which survived this interception were met by other fighters and 16 more were shot down. Of the remainder some made attacks on the destroyers Yarnall and Stockham, which were operating as pickets to the Battle Line, but the Japanese aircraft caused no damage. Three or four bombers broke through to the battleships, and one made a direct hit on South Dakota which caused many casualties but failed to disable her. Not one aircraft of Ozawa's first wave got through to the American carriers.
At 1107 radar detected another and much larger attack. This - Ozawa's second wave - consisting at this stage of 109 aircraft, was met by American fighters sixty miles out from Mitscher's flagship Lexington.
The first interception was made by 12 Hellcats, again from Essex, led by Commander David McCampbell, the highest-scoring US Navy fighter ace of the war. The Hellcats shot down approximately 70 aircraft from this raid. Most of the aircraft which broke through the combat air patrol were destroyed or driven off by the gunfire of the Battle Line.
Nonetheless, a handful of the bombers succeeded in attacking the American carriers.
Six attacked Rear Admiral Montgomery's group, making near-misses which caused casualties on two of the carriers. Four of the six were shot down. A small group of torpedo aircraft attacked Reeves' group just before midday, one launching a torpedo which exploded in the wake of Reeves' flagship Enterprise. Three other torpedo-planes attacked the light carrier Princeton, but were shot down.
In all 97 aircraft of this - Ozawa's second wave
- failed to return.
The third raid, consisting of 47 aircraft, came in from the north. It was intercepted at 1300, some 50 miles out from the task force, by 40 fighters. Seven Japanese planes were shot down. A few broke through and made an ineffective attack on Harrill's group. Many others did not press home their attacks. This raid therefore suffered less than the others, and 40 of its aircraft managed to return to their carriers.
After this third assault there was a brief lull in the battle. Several US carriers were able to secure from General Quarters, and Mitscher took the opportunity to launch a search mission - one which was, however, unsuccessful.
The fourth and final assault wave was launched from the Japanese carriers between 1100 and 1130. This raid was given an incorrect location for its targets. One group from this raid, failing to find anything at the reported position, headed for the island of Rota to refuel, but sighted Montgomery's task group by chance. 9 dive-bombers eluded the American fighters and made attacks on carriers Wasp and Bunker Hill, but failed to make any hits, and all but one of the attackers were shot down. Another group, of 18 aircraft from the Japanese carrier Zuikaku, lost half its number to the American fighters.
The largest group from this the fourth of Ozawa's raids, of 49 aircraft, failed to locate any US ships and made for Guam. It was picked up on radar and the last Combat Air Patrol of the day, 12 Hellcats from light carrier Cowpens, was sent to intercept. The US fighters came upon the Japanese planes as they were circling Orote Field ready to land. As the Cowpens aircraft went in to attack they were joined by seven Hellcats from Essex, again led by McCampbell, and eight from Hornet. These 27 US fighters shot down 30 of the 49 Japanese planes, and the 19 survivors which landed received heavy and irreparable damage.
While Ozawa's air groups were being devastated in this massacre his carriers had come under attack from American submarines.
At 0816 Albacore sighted Ozawa's own carrier division, and soon began an attack on the carrier most suitably placed, which by chance was the Taiho, Ozawa's flagship - the Japanese Navy's most modern and most strongly-constructed carrier. As Albacore was about to fire a salvo of six torpedoes at Taiho her fire-control 'computer' failed and her commanding officer, J.W. Blanchard, was forced to aim the salvo by visual judgment.
Taiho was than steaming at 27 knots. She had just launched 42 aircraft - her component of the Japanese second wave attacking Task Force 58. Four of Albacore's torpedoes were off-target. The pilot of one of Taiho's recently-launched aircraft - Sakio Komatsu - sighted one of the two which were heading for Taiho and heroically crashed his aircraft on it, destroying the torpedo but losing his life. Nonetheless the remaining torpedo struck the carrier on her starboard side near her aviation fuel tanks - but the damage to Taiho initially appeared to be not very serious.
Ozawa's Carrier Division also fell foul of the American submarine
Shokaku, one of the six carriers which had carried out the attack on
Pearl Harbor, was hit shortly before noon by three torpedoes of a
salvo of six which Cavalla had fired from the close range of 1,000
yards. Fuel tanks on the carrier were ruptured by the explosions,
fires spread through the ship, and at about 1500 a bomb magazine exploded,
Meanwhile the flagship Taiho was falling victim to poor damage-control. On the orders of an inexperienced damage-control officer her ventilation system had been operated full-blast in an attempt to clear explosive fumes from the ship. This instead this had the disastrous effect of spreading the vapours throughout Taiho, and at 1532, approximately half an hour after the explosion which sank Shokaku, Taiho was herself wrecked by a huge explosion, and sank shortly after.
Albacore and Cavalla were both subjected to heavy depth-charge attacks, but the submarines escaped without serious damage.
Of the hundreds of US aircraft engaged in this great battle only 23 were shot down, and 6 more lost operationally. Task Force 58 lost 29 aircrew and suffered 31 fatal casualties on the ships which were hit or near-missed. In very few battles since mediaeval times, whether on land or at sea, have losses been so one-sided.
The Final Phase - The Air Battle of 20 June
Task Force 58 pushed westwards during the night of 19/20 June in order to attack the Japanese fleet, and at dawn launched air searches. On the Japanese side there was great confusion caused by the fact that Ozawa attempted to control his forces from the destroyer Wakatsuki, to which he and his staff had transferred when the Taiho had to be abandoned. The destroyer's communications were inadequate for her to act as flagship, and at about 1300 on 20 June Ozawa transferred to the large carrier Zuikaku (sister ship to the Shokaku and as of 20 June the only survivor of the six carriers which had attacked Pearl Harbor). It was only now that Ozawa learned of the massacre of his air groups the day before, and that his force had only one hundred aircraft still operational. Nonetheless he was determined to continue the battle, believing that there were still considerable numbers of Japanese aircraft operational on Rota and Guam. Ozawa intended to launch further strikes on the following day, 21 June.
American searches failed, for most of 20 June, to find the Japanese
fleet, but eventually - at1540 - an Avenger piloted by Lieutenant R.S.
Nelson, from the veteran carrier Enterprise, found Ozawa's force.
Nelson's message reporting the contact was however so garbled that Mitscher
did not know what had been sighted or where. He nonetheless decided to
make an all-out strike when more information came in, despite the fact
that there were now only about 75 minutes to sunset, and that the strike
would therefore have to be recovered in darkness. By 1605 further reports
from Lt. Nelson had given the Task Force 58 commander the information needed.
At 1610 the aircrew manned their planes, and at 1621 the carriers turned
into the wind to launch the strike. The launching - of 216 aircraft - was
completed in the remarkably short time of eleven minutes.
Grumman TBF Avenger
The attack went in at 1830. Ozawa had been able to put up very few fighters to intercept - no more than 35 according to the American pilots' later estimates, but these few were skilfully handled, and the Japanese ships' anti-aircraft fire was intense. The first ships sighted by the US strike were oilers, and two of these were damaged so severely that they were later scuttled. The carrier Hiyo was attacked by 4 Avengers from the light carrier Belleau Wood and hit by at least one of their torpedoes. The carriers Zuikaku, Junyo and Chiyoda were damaged by bombs, as was the battleship Haruna. The torpedoed Hiyo later sank. Roughly 20 American aircraft were lost in this strike.
By nightfall on 20 June Ozawa had therefore lost three carriers, including two of his finest ships, and of the 430 aircraft which had been available to his force on the morning of 19 June only 35 were still operational.
Mitscher - who invariably showed unusual concern for the safety and well-being of his flyers - then took the decision to fully illuminate the carriers, despite the risk of attack from submarines and night-flying aircraft. All ships of the task force turned on their lights, and the screening destroyers fired starshell throughout the recovery, which lasted two hours. Despite these measures eighty of the returning aircraft - with pilots neither trained nor equipped for night landing - were lost, some crashing on flight decks, the majority going into the sea. But of the 209 aircrew participating in the 20 June strike 160 were rescued either during the operation or in the following few days.
The two-day engagement had been the largest pure carrier-versus-carrier battle in history, and was to be the last. The immediate consequence of the Japanese defeat was the US capture of the Marianas. This broke the Japanese inner line of defence, and meant that American bombers based in the islands could now reach targets on Japan itself. As a result of their huge losses of aircrew in the battle the remnants of the Japanese seaborne air groups were never again able to challenge the American fleet, and at the Leyte Gulf four months later the Japanese carrier force - which had once dominated the Pacific War - was reduced to playing the role of decoy, while the primary attacking role was, of necessity, assigned to the Imperial Navy's battleships and their attendant cruisers and destroyers.
The main source for this narrative was Samuel Eliot Morison's
"History of US Naval Operations in World War II" (Little, Brown & Co, Boston)
Volume VIII "New Guineau and the Marianas."
The profile drawing of the A6M Zero fighter is of a land-based
version in the markings of the Genzan Air Corps.
It is reproduced with thanks from "Combat Aircraft of World War II" by W. Gunston (Spring/Salamander).
The drawings of the Avenger and Hellcat are reproduced,
with thanks, from
"Jane's War at Sea 1897-1997" by B. Ireland & E. Grove.
The Big Controversy - Spruance's Decision, 18-19 June
The United States Order of Battle
The US Fast Carrier Task Force
Ships of the Fifth Fleet - Illustrations
Japanese Forces - The Mobile fleet