Hailstone on Truk


Japanese ammunition ships in Truk Harbor explode following a torpedo attack by a US carrier based plane. The pilot and two crew-members of this plane are presumed to be lost since their plane were caught in this terrific explosion. 17 February 1944.


A Japanese freighter in Truk Atoll is hit by a Mark XIII torpedo dropped from a Grumman TBF Avenger of Torpedo Squadron 17 (VT-17) from the aircraft carrier USS Bunker Hill (CV-17), 17 February 1944. Fighting alongside VT-17 in task force 58 was VT-10. Including the ground-breaking night attack of 16-17 February, VT-10 accounted for one third of the total shipping destroyed by the Task Force 58 attack on Truk Atoll. Note the several torpedo wakes, including one very erratic one ending with the torpedo broaching. The photograph is discussed by the photographer W. Eugene Smith in the June 1944 article entitled Camera on a Carrier that appeared in Popular Photography. The aircraft that dropped the successful strike shown in the photo was flown by Lt. Paul Eugene Dickson.


Operation Hailstone was intended to remove Truk from the equation. Fast Carrier Forces Pacific Fleet mustered five fleet carriers, including veteran USS Enterprise and four new Essex-class ships, and four light fleet carriers, with a total embarked force of roughly five hundred aircraft. To prevent escape the US deployed its growing submarine force on the routes the Japanese could take to do so, while surface ships, including brand-new Iowa-class battleships, would be deployed during the battle to search for possible escapees. The US carrier forces had proved that they could crush a land base during the pre-invasion strikes on the Marshalls. Now they would try their hand at one that was actually well-defended.


Devastation: A recon photo taken on the second day, showing damage to the shore facilities on Dublon Island.


The IJN had built up its web in the South Pacific around the main advanced base of Truk Atoll, in the Caroline Islands. Legend had made it seem like an impregnable fortress, but in point of fact it was only lightly defended, in terms of guns and fixed installations, and its offensive strength depended upon the presence of the Combined Fleet and the capacity of the ‘rear areas’ of the Palaus and Saipan to pass on air reinforcements and the necessary supplies to maintain the fleet. Its defensive strength had depended upon the outlying island groups, the Solomons, Gilberts and Marshalls, whose air garrisons would at best divert attack and at worst give warning. With the neutralisation of Eniwetok in early February the way was clear for an undetected approach by the USN’s carriers.

Task Force 58 had come through Flintlock with a minimum of casualties; nineteen Hellcats, fourteen Avengers and three Helldivers from Task Groups 58.1, .2 and .3. Not one of the old, slow and utterly reliable Dauntlesses had been lost. After replenishing at Majuro from 4 February, individual Groups alternated in providing patrols over Kwajalein and distant support for the preliminary operations off Eniwetok Atoll, until Roi Airfield became operational for search aircraft. By 10 February all three Groups were resting at Majuro, where replacement aircraft were furnished by the replenishment carriers of Service Squadron 10, the ‘train’ of oilers, stores ships, ammunition ships, hospital ships and other auxiliaries which had been formed to support the fast carrier task force. Majuro was being developed into a major base by the provision of repair ships, a floating dock, large supply dumps ashore and a bomber-size airfield which was to be used for the storage of reserve carrier aircraft. By the end of the month, after all losses had been made good, there were three dozen F6Fs, forty-two SBDs and a smaller number of TBFs, as well as ten F4Us of a USMC squadron to provide local defence.

Operation Hailstone, the attack on Truk, had originally been scheduled to coincide with the assault on Eniwetok Atoll, but as soon as the decision was made to advance the latter operation Admirals Spruance and Mitscher began planning for the strike. By 10 February permission had been granted by CinCPAC. Not only would cover be provided for the Eniwetok landings, but the next move planned for Admiral Halsey’s Third Fleet, the occupation of Green Island, would also be assisted.

The latest reconnaissance of Truk had disclosed the presence of the majority of the serviceable units of the Combined Fleet, as well as the converted carrier Kaiyo, which was delivering the 551st Air Group. What was not immediately known was that the appearance of the USMC PB4Ys had caused a precipitate flight of major units, dispersed to Japan and Singapore to leave just two old light cruisers and four destroyers. There were also over fifty merchant ships and auxiliaries left in the lagoon; ships damaged by American air and submarine action, or simply unable to complete unloading in time.

Task Force 58 sailed from Majuro on 12 February, less TG 58.4, already at sea and in action off Eniwetok. All five large and four light carriers were present, but only six out of eight battleships were serviceable. Indiana and Washington had collided off Kwajalein in the early hours of 1 February and had been obliged to return to the USA for repairs. The carriers were stronger in one respect. During the rest period at Majuro four-aircraft flights of nightfighters had been embarked in four of the carriers. Corsairs of VF(N)-101 were aboard Enterprise and Intrepid, while the first F6F-3Ns, of VF(N)-76, went to Yorktown and Bunker Hill.

The Task Force refuelled on 14 February, 115 miles to the northeast of Engebi Island. During the afternoon the Belleau Wood CAP was directed to a G4M search aircraft from Truk; the enemy aircraft was destroyed before it had sighted the Force, and even before it could pass a distress message. Its failure to return alerted Truk to the likelihood of a sudden descent by the carriers, but a shortage of long-range search aircraft prevented full search patterns from being flown, and Task Force 58 reached its flying-off position undetected, 90min before dawn on 17 February 1944.

On arrival the light carriers began to launch the CAP for the Task Force, which was operating with its three Groups manouevring independently, but within visual distance of each other. As the CAP reached its various stations, the large carriers began to launch a fighter sweep of seventy Hellcats, led by Commander R. H. Dale of Bunker Hill, who was to co-ordinate the initial air-superiority strikes. The islands of Eten, Dublon, Param and Moen were a little more than 100 miles from the launching position, and although the Japanese air warning radar detected the sweep shortly after it had taken departure from the Task Force, internal communications were inadequate and the defences were ill prepared. About eighty aircraft, mostly A6Ms, managed to get airborne, but only forty-five of these were in tactically favourable positions to meet the Hellcats. Another 230-odd were still on the ground on Eten, Moen and the Param seaplane base. These aircraft represented nearly two-thirds of the JNAF’s total strength in the Central Pacific, and were a combination of all types, primarily single-engined. The personnel of 22nd and 26th Air Flotillas had had neither the time nor the prepared revetments to disperse their aircraft effectively, and although the majority were serviceable the inconvenience of dispersal of aircraft on one island and the pilots on another prevented more from escaping by flying away.

The F6F sweep immediately destroyed thirty of the A6Ms which opposed them and then went on to strafe the crowded airfields, where forty assorted types were destroyed or seriously damaged. Hard on the fighters’ heels came eighteen Avengers, six from each Task Group, to drop fragmentation and anti-personnel bombs on the aircraft. Over 100 enemy aircraft were now broken and burning on the ground, and as more attack and floatplane types took off to escape they were shot down by the fighters, which maintained a standing patrol over Truk throughout the day.

Once air superiority had been achieved in this dramatic fashion, all the carriers began to launch individual strikes against the shipping, some units of which were already beginning to leave by the various ‘passes’ in the reef. A considerable amount of attention was devoted to the light cruiser Katori and two attendant destroyers, strikes by Yorktown’s CVG-5 being followed by less coordinated attacks from the other carriers. The cruiser and one destroyer were both damaged badly, but the other destroyer, Nowake, avoided the twelve 1,000lb bombs and six torpedoes aimed at her and escaped both the air and, later, surface attacks. Attacks on the shipping in the lagoon were more gratifyingly productive. The targets had less freedom to evade the bombs and torpedoes, although they did have the benefit of greater protection under the formidable AA umbrella. Some twenty individual antishipping strikes were delivered during 17 February, the strength of each varying between eighteen and thirty aircraft. Not until the last strike of the day was further attention paid to the airfields, when Avengers dropped 2,000lb delayed-action bombs to disturb the enemy’s peace during the hours of darkness.

The anti-shipping activities were not limited to the carrier aircraft. Admiral Spruance took his flagship, New Jersey, and another battleship, Iowa, two heavy cruisers and four destroyers on an anticlockwise sweep around Truk, closing to within sight of the reef on occasion. Hellcats of VF-25, from Cowpens, maintained a CAP over the Group (50.9), which had intended to use its own OS2Us for searches. In the event, so many carrier aircraft were only too willing to provide information that the use of the floatplanes proved unnecessary. When the battleships overtook Katori and her two destroyers, Bunker Hill’s Air Group Commander was again on hand, this time to spot for the fall of shot which sank the two already-damaged ships. Later in the afternoon an SBD of VB-6 that attempted to drop a message to Iowa was shot down by the ship’s overenthusias-tic 20mm batteries. A dozen aircraft of this squadron had found and attacked a convoy 100 miles to the west of Truk, and the leader had been attempting to inform TG 50.9 of the presence of a stopped tanker and a damaged freighter within two hours’ easy steaming distance.

The VF-25 CAP arrived an hour after the Task Group had detached from Task Force 58, and a few minutes after a single A6M had appeared without warning from the low cloudbase and near-missed Iowa with a light bomb. This fighter-bomber was subsequently shot down by the CAP, as were two others which made similar unheralded attacks on the Group. Shortly before the last division had to depart for a dusk recovery, a pair of F1M ‘Pete’ floatplanes arrived, presumably to shadow the battleships. These were quickly destroyed and Task Group 50.9 passed an undisturbed night, rejoining the main body at dawn on the next day. The CAP’s other major contribution of the day had been in giving warning of approaching torpedoes during the action with the naval units. Both Iowa and Minneapolis were fortunate to avoid torpedoes whose presence had been broadcast by the Hellcat pilots.

No sooner had the last USN aircraft over Truk departed, half an hour before sunset, than the Japanese began to prepare a retaliatory strike. Few aircraft were available, but six B5N ‘Kates’ took off at dusk and the first was detected by Task Force 58’s radar an hour later. The B5Ns were equipped with the first airborne radar to be encountered by the American carriers, so that there was not the usual display of flares and float lights to herald an attack. Two hours elapsed before any really threatening run-in started; earlier runs by single aircraft had been easily discouraged by turning the Task Force away to present the torpedo-bomber with an unfavourable approach from astern. Only on two occasions had the attacker closed to within AA range before an F6F-3N of VF(N)-76B was launched from Yorktown, to deal with a single B5N which had been circling at a distance of some 40–45 miles for over an hour.

Twenty minutes after the nightfighter had taken off, the torpedo-bomber began to head for the Task Force, and Enterprise’s more experienced fighter direction team took control of the Hellcat, vectoring it towards the B5N, which was descending slowly as it approached. The Hellcat pilot gained fleeting radar contact when both aircraft were about 20 miles from the screen, but contact was not regained and the B5N continued its 120kt low-level approach. The ships were ordered not to fire as the Hellcat was still searching for the enemy aircraft, so the B5N pilot had only to contend with the carriers’ evasive manouevres. As Intrepid was turning hard to avoid the attack she was hit right aft on the starboard side. The ‘Kate’ escaped.

Intrepid was still capable of making 25kts, but her rudder was jammed hard over, and only by running the two screws on the other side at near-maximum revolutions could she maintain a straight course. Eleven men were killed and a number wounded. Within two hours of the attack Intrepid had been detached to proceed to Eniwetok, covered on passage by Cabot, two cruisers and four destroyers.

As soon as the B5Ns had withdrawn, Enterprise began to launch the sixteen TBF-1Cs of VT-10, each armed with four 500lb bombs. The squadron, commanded by Lieutenant Commander W. I. Martin, had worked-up as a night-strike unit during the preceding six months, and the 30min they spent over Truk lagoon fully justified the effort. Using their ASB radar to find and approach their targets, the Avengers sank some 60,000 tons of shipping and scored two direct hits on islets mistaken for ships. All returned safely.

A fighter sweep opened the proceedings on 18 February, but on this occasion there was no opposition at all, apart from the AA fire. Another ten anti-shipping strikes were delivered during the forenoon, finishing off damaged ships and adding further casualties to the list. By midday, when Task Force 58 began its retirement, 400 tons of bombs and sixty-six torpedoes had been delivered by 616 dive-, glide- and torpedo-bombers. At a cost of three SB2Cs and SBDs, and six Avengers, the carrier strikes had sunk a light cruiser (Naka), two destroyers, six large modern naval auxiliaries, five tankers (one of 19,200 tons), nineteen freighters, two patrol craft and an armed trawler. The loss of nearly a quarter of a million gross register tons of such valuable transport shipping was a catastrophe for the Japanese cause at this stage of the war. Such tenuous links as had been preserved with Rabaul via Kavieng were now broken, for after this devastating raid Truk was hardly to be regarded as a secure base.

The aircraft losses were equally serious. After careful assessment, discarding dubious or insufficiently substantial claims and applying a factor to take account of duplicated claims in air combat, and relying wholly on photographic evidence for the extent of damage to aircraft on the ground, Task Force 58’s intelligence staff put Truk’s losses at 279 aircraft. Of these, seventy-nine were A6Ms and D4Y2s (the latter were frequently mistaken for Kawasaki Ki-61 ‘Tony’ JAAF fighters at this period), and fifty other types shot down by the fighters, which lost only three of their own number in air combat. On the ground, another 152 aircraft had been either destroyed or badly damaged. Five more Hellcats had been shot down by AA fire.

Damage to installations on the islands was relatively insignificant. Until the time of the very last strike of the operation, claims were limited to just three hangars destroyed and an ammunition dump blown up. The prizes reserved until the end were the oil storage tanks on Dublon and Eten Islands. The bombs broke and set fire to the tanks and their contents, producing dense clouds of black smoke which formed an impenetrable blanket across the lagoon, demonstrating why these attractive targets had been left untouched previously. Only 94 tons of bombs were dropped on targets ashore.

As well as the seventeen aircraft lost in combat, eight were lost operationally. Only eight of the aircrew shot down were rescued, but this was made up in part by the fact that only three of the thirteen aircrew involved in operational losses were not picked up. The battleship and cruiser floatplanes were active in searching and retrieving aviators. An OS2U from Massachusetts flew 80 miles to rescue a VF-25 pilot who had ditched near TG 50.2, and Baltimore’s floatplane actually landed in Truk lagoon to pick up a VF-9 pilot. The personnel losses were proportionately the highest suffered since August 1943, but in view of the nature of the target, defences, and results, the price paid for Hailstone was not exorbitant.

No Japanese aircraft interfered with Task Force 58 until the early hours of 19 February, as the ships passed to the north of Ponape. Radar-equipped G4Ms attempted to attack, but one of the pair was shot down by AA fire and the other was driven off by a Corsair nightfighter from Enterprise.

During replenishment on the 19 th the Task Force was reorganised. Yorktown and Belleau Wood joined Essex in Task Group 58.2, and the battleships and cruisers were redistributed. Admiral Spruance departed in New Jersey, bound for Majuro with a small screen of destroyers. Enterprise also left TF 58 for Majuro, but en route her aircraft struck at Jaluit. During the afternoon of 20 February sixty-six sorties were flown against the limited shore establishments and port installations on the atoll. Four aircraft were damaged by AA fire and 27 tons of bombs were dropped. The crippled Intrepid arrived at Eniwetok for emergency repairs on the 22nd, having spent the previous two days under sail, using a makeshift quilt of spare canvas and tarpaulin which had to be rigged to keep her closer to the wind after the weather worsened on 19 February.

Admiral Mitscher was now in full command of his remaining six carriers, with orders to carry out an even bolder strike than that just delivered against Truk. The targets were to be the Marianas Islands of Guam, Saipan, Tinian and Rota, 1,455 miles south-southeast of Tokyo and 1,150 miles to the west of Eniwetok. As well as being key stepping stones for the aerial reinforcement of the Caroline Islands, the Marianas airfields were vital for the protection of the approaches to the Philippines, Formosa and the northern part of the Philippine Sea. With Truk so reduced in stature after the strikes, the IJN took vigorous and immediate steps to strengthen the Marianas against possible attack. The planned move of part of the First Air Fleet was advanced, and on 20 February the first units were moved in. Further movements were hampered by bad weather on the route. The Japanese had responded quickly to a potential threat, but they could not have foreseen how quickly that threat would materialise.

The recently-deployed First Air Fleet units included a high proportion of aircrew undergoing operational training, but nevertheless effective searches were flown by the few experienced crews and the instructors who had accompanied their pupils. A G4M sighted Task Force 58 shortly after dark on 22 February, when it was still 470 miles to the east of Saipan. Three waves of torpedo-bombers, twenty G4Ms in all, took off and attacked Task Group 58.3 almost continuously from midnight until shortly before dawn. The direction of the wind was not suitable for flying from the carriers, which would have been obliged to turn away from the Marianas to operate aircraft, at a time when the main object was to close the distance as quickly as possible. Accurate AA fire and hard manouevring saved the ships from damage, and only five of the twenty ‘Bettys’ returned to their base on Tinian.

The airfields were the main targets for the carrier strikes, which were launched before dawn from a position 100 miles to the west of the islands. The dawn fighter sweep technique which had proved so effective over Truk was again employed, and again the results were catastrophic for the JNAF. The Hellcats swept the A6Ms aside and, supported by follow-up strikes by dive-bombers and Avengers, they practically destroyed the recent reinforcements. Numbers destroyed are almost impossible to ascertain, varying between 95 and 168, with a reasonable mean of 115; 30 in the air and the remainder on the airfields. The biggest harvest was reaped by Task Group 58.3’s strikes on Tinian and Rota, where most of the defensive fighters were encountered. Task Group 58.2’s effort against the other two islands was limited by a preoccupation with the possibility that the carrier Chitose might be approaching with either an operational Air Group or reinforcement aircraft for the Marianas. Yorktown was allocated the task of searching for and striking at the enemy carrier, and her contribution to the attacks on Saipan and Guam was accordingly limited. CVG-5 failed to find the carrier, which had not yet left the Inland Sea, but the SBDs and TBFs sank two freighters, totalling nearly 10,000 grt, and a number of small escorts and patrol craft. One very important mission for Yorktown’s aircraft was the collection of a set of photographs of the Saipan coastline, needed for planning for the assault which was to come.

Enemy aircraft, D4Ys and the new Nakajima B6N ‘Jill’ torpedo bombers, made poorly co-ordinated attempts to strike back, but these raids were broken up at long range and none penetrated to within gunnery range of the Task Force.

The Task Force withdrew shortly after noon. Nearly 400 sorties had been flown and over 140 tons of bombs and rockets had been released against the islands. Five Hellcats and an Avenger had been lost to flak and the fighters. After a mid-ocean replenishment the Groups were reorganised yet again. Essex and Cowpens proceeded to Pearl Harbor for routine maintenance at the Navy Yard, while Bunker Hill, Belleau Wood, Yorktown and Monterey returned to Majuro, to rejoin Enterprise, Princeton and Langley. Intrepid and Cabot left Eniwetok towards the end of February, arriving at Pearl Harbor on 4 March. At the same time Saratoga began a long passage via Efate, Sydney and Fremantle (Western Australia) to join the Royal Navy’s Eastern Fleet at Trincomalee in Ceylon. Her operations with HMS Illustrious are recounted in the section covering Royal Navy operations.

From 23 February the land-based Task Force 57 assumed full responsibility for the air defence of the Marshall Islands. By the 29th there were 120 USMC Corsairs and twenty-eight Dauntlesses based on Engebi, Roi, Kwajalein and Majuro. More single-engined aircraft were about to move up from the Gilberts, where the long-range bombers and reconnaissance machines were still based. Roi was already capable of providing staging facilities, and on 29 February six USN PB4Ys from Abemama refuelled there for a raid on Wake Island, a 3,000-mile round trip which took 20hr.

February 1944 was the most significant month of the war in the Pacific. The American fast carriers had demonstrated the flexibility, mobility and striking power which form the bases of victory at sea. Supported by the three CVE Groups, Task Force 58 had flown over 8,000 sorties around the Marshalls, over Truk and among the Marianas. The equivalent of an Essex-class Air Group had been lost, forty-five aircraft in combat and thirty-five operationally, but the enemy losses were out of all proportion. More than 500 Japanese naval aircraft had been destroyed, as well as over fifty ships, large and small. Above all, the carrier force had demonstrated its ability to roam freely, achieving air superiority not only over its own immediate vicinity, but also over enemy airfields. For the Japanese, a maritime nation with its survival dependent upon imported raw materials and its defences dependent upon freedom of air and surface passage between a network of island strongholds, this freedom would mean ultimate defeat if allowed to continue. Only by bringing Task Force 58 to battle and inflicting a substantial defeat could the IJN gain time to rebuild an all-conquering fleet.

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