Hail Storm at Truk

Two hours before daybreak on 17 February 1944, at a location so secret and remote that no Westerner had set foot in the vicinity for 20 years, five U.S. fast carriers prepared to launch some 70 F6F Hellcat fighters, the leading edge of one of the most powerful naval striking forces ever assembled.¹ Their target was Truk Atoll, about 90 miles southwest of the carriers, believed by U.S. intelligence to be sheltering the strongest naval base in the Pacific between Pearl Harbor and Japan.² The U.S. Navy was bent on reducing it to rubble and turning its lagoon into a graveyard for the Imperial Japanese Navy’s Combined Fleet.

The task would be difficult, and operational surprise was unlikely. Truk’s geography presented acute problems for any attacker. In the middle of the Caroline Islands, west of the Marshalls, it was part of the territory ceded to the Japanese after World War I. Truk is 955 miles from Kwajalein—which had been captured by U.S. forces at the beginning of February 1944—and some 3,075 miles southwest of Pearl Harbor. The nearest Japanese base was only 175 miles away at Nomoi, and other bases in the Marianas were less than 600 miles distant. The mighty South Seas fortress of Rabaul was just less than 700 miles to the south. The Japanese used Truk, in fact, as a way station for ferrying aircraft from Japan to Rabaul.³

The atoll’s layout made it a superb ' fleet anchorage, easily defended against amphibious assault. The lagoon, surrounded by a coral barrier reef, is roughly 30 miles in diameter. Inside the lagoon are six large volcanic islands: Tol, Dublon, Moen, Udot, Uman, and Fefan. These, plus 78 other islands and islets, comprise the land portion of the atoll. In 1944, Moen, Param, and Eten islands had airfields, and Moen and Dublon had seaplane bases. The lagoon covers approximately 500 square miles, with only five navigable passages through the encircling reef. These known geographic features, a profound lack of knowledge about Japanese preparedness at Truk, and rumors of enemy fortification of the atoll beginning in the 1930s all produced an air of deep foreboding among the men of Vice Admiral Raymond A. Spruance’s Central Pacific Force. Truk, apparently, would be a tough nut to crack.

For more than two years of war, Truk had remained beyond the reach of strategists in Pearl Harbor and Washington. Its status as a principal anchorage of the Combined Fleet made it a tempting but dangerous target. A large-scale attack on Truk could be managed only after the capture of the Gilberts and key locations in the Marshalls. Risking substantial fleet assets under any other conditions would have been folly, given the preponderance of Japanese land-based air power in the region. But an intense debate still raged in the U.S. command in February 1944: should Truk be invaded, or just raided from the air? At the time of Hailstone—the code name for the two- day naval operation intended to reduce Truk as an operating base and annihilate naval and merchant shipping in its vicinity—no one had made a decision regarding invasion. If the results of Hailstone were favorable, then invasion likely would be deemed unnecessary.

The Japanese had done much to promote the image of Truk as a bastion of overseas naval might, but leaders of the Imperial Navy knew better. Its resemblance to a fortress came from its natural geography and little else. The Imperial Navy’s 26th Air Flotilla was stationed at Truk, but the Japanese did not consider air defense of the atoll to be adequate. According to a postwar assessment by the U.S. Strategic Bombing Survey, the entire atoll contained only 40 antiaircraft guns, none of which was directed by fire-control radar.⁴ Command arrangements were confused and inadequate. The official Japanese report on action at Truk notes that the naval base forces there were under the Southwest Pacific Command, operational aircraft under the command of the Combined Fleet, and training units under the Southeast Pacific Command.⁵ Army troops on the atoll (elements of the 52d Division) were not subordinated to Navy command at all. The complexity of these command arrangements was such that effective defensive coordination in the face of a U.S. attack was rendered impossible.

The U.S. advance into the Marshalls began in late January 1944, with landings at Majuro and Kwajalein. The Combined Fleet sortied but shied away from a confrontation with Admiral Spruance’s powerful forces and returned to Truk without firing a shot.⁶ The next target for invasion was Eniwetok Atoll, lying 285 miles northwest of Kwajalein and only about 670 miles from Truk. U.S. commanders decided that no attempt to capture Eniwetok could proceed without also attempting to neutralize Truk. To that end, simultaneous operations were planned: Operation Catch- _pole was the code name for occupation of Eniwetok, which would be supported by Task Group 58.4 (including the carriers Saratoga [CV-3], Princeton [CVL-23], and Langley [CVL-27]), under the command of Rear Admiral S. P. Cinder; meanwhile, Operation Hailstone would proceed, employing the other three task groups of Rear Admiral Marc A. Mitscher’s Task Force 58, including nine carriers and six battleships.

In the minds of U.S. Navy strategists, Hailstone was the more critical operation, not only because Truk was an important base in its own right, but because of the presumed presence of the Combined Fleet and the fact that Truk represented the anchor of the next Japanese defense line beyond the Marshalls. Moreover, the U.S. command considered the neutralization of Truk as a necessary step in the larger campaign to isolate Rabaul, which forces under General Douglas MacArthur’s command in the Southwest Pacific and Admiral William F. Halsey’s command in the South Pacific were already pounding from the air. If Spruance could have delivered a crippling blow to Truk at this point in the war, he could have made a major dent in the Japanese central defense perimeter, holding important implications for the conduct of operations in the Marianas, Bismarcks, Solomons, and New Guinea.

The first act in the move to reduce Truk occurred on 4 February, when a lone Marine PB4Y Liberator flying from Bougainville in the Solomons (a distance of 850 miles) took reconnaissance photographs of the atoll that clearly indicated the presence of a substantial portion of the Combined Fleet. The photographs revealed that 1 battleship, 2 carriers, 9 or 10 cruisers, 20 destroyers, 12 submarines, and a large number of dry cargo ships were actually present at Truk during the first week of February.⁷ The Japanese noted the appearance of the Liberator and rightly took it as an ominous sign. Admiral Mineichi Koga, Isoroku Yamamoto’s successor as Commander-in-Chief, Combined Fleet, did not want a major fleet engagement on U.S. terms. Acutely aware that “Fortress Truk” was nothing more than a myth, Koga determined to pull his fleet back to Palau and await further developments.⁸ By 10 February, the fastest elements of the Combined Fleet had departed Truk, never to return. Remaining, however, were a large number of merchant ships, which did not have priority under the prevailing conditions of fuel shortage, and which needed time to unload their cargoes. In addition, a few smaller combatants, naval auxiliaries, and submarines stayed at Truk, though their withdrawal, too, was anticipated.

The U.S. forces failed to detect Koga’s retreat in the face of danger, and U.S. planning proceeded on the assumption that large Japanese fleet elements would be present on the date of the operation. For some reason never explained, the Japanese high command came to believe that no U.S. strike against Truk was likely before 21 February.⁹ But on the 15th, the disappearance of a Betty bomber that had been sent eastward on a routine scouting patrol fueled Japanese fears of attack. Imperial Navy officials speculated that the plane had been shot down by U.S. aircraft, which was, in fact, the case.¹⁰ In addition, the Japanese radio intercept group on Truk had picked up voice transmissions that it correctly identified as relating to U. S. carrier operations, because they contained “color” base call signs.¹¹ Accordingly, they finally placed the atoll on alert. Early on the 16th, six aircraft flying 300-mile legs from Truk conducted a special search to the north, but the search covered only a 60° arc and no U.S. ships were sighted.¹² Apparently convinced that they were in no immediate danger of attack, and concluding that the intercepted voice transmissions of a day earlier had emanated from a point far to the east, the Japanese stood down their alert.

In the meantime, Spruance’s three task groups—representing more than three-fourths of Task Force 58’s strength—moved toward their positions for the predawn launch on the 17th. Mitscher had formulated the operational plan for the strikes, which was a model of efficiency. The idea was to fly planes over the atoll continuously, from dawn until practically dusk, giving the Japanese no respite and no time to regroup during the day. The initial fighter sweep was intended to eliminate air opposition over the target and incapacitate Japanese fighter aircraft on the ground; bombing raids against the airfields were to follow. Ships in the lagoon would be strafed and bombed, and those outside the lagoon would be attacked as circumstances allowed. In order not to obscure other targets, oil storage facilities on Dublon and Eten were slated for destruction on the second day.

Launch of the initial wave of 70 Hellcats commenced at 0450, 17 February. The weather was fair with good visibility, as the planes arrived in the target area just before sunrise (about 0605), and the Japanese were largely unprepared to deal with them. Though the airfield at Param had 30 minutes’ warning of the attack, Eten had only ten minutes’ warning and Moen none at all. In addition, Japanese radar stations were not adequately manned, telephone communications were poor, and many Japanese pilots were caught out of position— their planes were on Moen and Eten, while the pilots themselves were on Dublon.¹³

At the time of the raid, 365 Japanese aircraft were on the atoll, a number that included some 200 in transit, mostly earmarked for Rabaul and awaiting ferry pilots. The majority of the in-transit aircraft were fighters, and the Japanese had lined up most of them nose-to-tail on Eten.

As the Hellcats swept down on Truk, about 45 Japanese fighters attempted to intercept them, and several dozen others were in the process of taking off. What ensued was a wild melee, the extent of which was unprecedented in the Pacific war. The Hellcats approached in three groups: VF-10 from the Enterprise (CV-6) and VF-5 from the Yorktown (CV-10) flew low attack; VF-9 from the Essex (CV-9) and VF-6 from the Intrepid (CV-11) ran the intermediate attack; and the Bunker Hill’s (CV-17) VF-18 flew high cover. Lieutenant Commander William R. (“Killer”) Kane of the Enterprise’s VF-10 led the sweep, and after making one strafing pass over Moen, encountered Zekes in the air. Within five minutes, he and his wingman had downed five enemy planes, as more than 30 of the would-be interceptors were shot out of the sky.¹⁴

After dispatching the enemy fighters, Kane and his pilots resumed their strafing runs on the Japanese aircraft remaining on the ground. The result was an additional 40 planes destroyed on Moen, Eten, and Param. Hellcat losses in this first action over the target were comparatively light: four F6Fs from all causes, at least one of which was reported to have been downed by another Hellcat.¹⁵ All told, the Hellcat squadrons spent less than an hour over Truk, but the damage they inflicted effectively deprived the atoll of its fighter defense.

Following on the heels of the Hellcats was the first wave of bombers. Sixteen TBF Avengers flying from Task Group 58.1 ’s Enterprise and Yorktown riddled aircraft dispersal areas on Moen, Eten, and Param with fragmentation clusters, incendiaries, and 500-pound general-purpose bombs. The Yorktown’s TBFs also attacked shipping in the lagoon. At the same time the Avengers pummeled these targets, some 25 SBD Dauntless dive bombers, all from the Enterprise and the Yorktown, attacked 30 ships at the Moen and Eten anchorages with 1,000-pound general-purpose bombs. The seaplane tender Akitsushima provided a visible and vulnerable target and took two hits from 1,000- pounders, but did not sink. Ships in the anchorages threw up a hail of inaccurate antiaircraft artillery, including a heavy volume of small-caliber fire. Just as the bombers from Task Group 58.1 were pulling away from their targets, aircraft from Task Group 58.2’s carriers Essex and Intrepid began their own attacks on shipping off Eten and Dublon. The carriers Bunker Hill and Cowpens (CVL-25) of Task Group 58.3 launched a similar attack against shipping in the vicinity of Dublon and Moen, with the Cowpens’ aircraft hitting the Moen fighter strip as well.

The pounding of Truk and its shipping continued as scheduled on a rolling basis throughout the day. The result was devastation of both shipping and shore installations. The majority of merchant vessels had been anchored in the lagoon when the first carrier planes appeared, and despite heavy antiaircraft fire from the warships present, they were easy targets for the U.S. fliers.

In the midst of the air attacks, however, a number of ships in the lagoon made runs for the navigable passages through the reef. Merchant vessels of Armed Convoy 4215 and their naval escorts were under way and moving toward the North Pass, when the first wave of carrier planes descended on Truk. Aircraft involved in the first strike of the day reported seeing these ships moving toward the north end of the reef. Later reports indicated that some of the ships had cleared the Pass and were at least ten miles outside the reef, when aircraft from Task Group 58.1 located the ships on their second strike. Targets included the Akagi Maru (a large cargo ship), the light cruiser Katori (a training ship), and the destroyers Maikaze and Nowake. Hellcats from the Enterprise and the Yorktown strafed these ships, and the Enterprise’s Avengers dropped 1,000-pound bombs on the Katori, with hits scored amidships and on her bow. At about 0800, Avengers attacked the light cruiser Naka outside the lagoon; later in the day Dauntlesses sank her. Two destroyers, the Shigure and the Harusame, slipped through the North Pass after 0700, even though they had endured attacks from a total of about 45 aircraft. The Shigure was damaged significantly, but both ships, along with the fleet repair ship Akashi, were able to escape to Palau.

While the air attacks continued, at 0926 Admiral Spruance formed Task Group 50.9, a surface-action force created out of Task Group 58.3. He left Mitscher in tactical command of the three carrier groups while retaining command of Task Group 50.9 from his flagship, the USS New Jersey (BB-62). The force consisted of the battleships New Jersey and Iowa (BB-61), the heavy cruisers Minneapolis (CA-36) and New Orleans (CA-32), and the destroyers Izard (DD-589), Charrette (DD-581), Bradford (DD-545), and Bums (DD-588). After formation of the new group, Spruance commenced a counterclockwise circumnavigation of the atoll with the intention of intercepting and destroying any ships trying to escape.

The new task group proceeded in a westerly direction at a speed of 25 knots, and at 1215 an aerial observer reported the presence of a number of vessels 20 to 30 miles directly ahead of the U.S. force. These were the ships from Convoy 4215 that had already been battered by air attack and were ablaze. About an hour after the first report, Task Group 50.9’s destroyers opened fire at 15,000 yards, leaving the ammunition trawler Shonan Maru dead in the water. Gunfire from the New Jersey subsequently destroyed her. Attention then shifted to the light cruiser Katori, her bridge smoking from air attacks. But she fought back gamely with her forward guns against the impossible odds. The Bradford and the Bums put two torpedoes into her, and she was finally sunk by 8-inch fire from the Minneapolis and the New Orleans, though not before she lay a spread of torpedoes that narrowly missed the U.S. cruisers. Meanwhile, the destroyer Maikaze came under fire from other ships in the group, which succeeded in sinking her at 1340, about 20 minutes after the action began. The destroyer Nowake was there during the engagement but to the west of the other Japanese ships and though straddled by 16- inch fire from the New Jersey and the Iowa, was able to outrun her pursuers.

Some two hours after ceasing fire on the Nowake, the destroyer Bums sank a Japanese subchaser west of Truk. This action was the last encounter Task Group 50.9 had with the enemy, as Spruance completed his sweep and rejoined the carrier groups about 0630 on the 18th. During Spruance’s circumnavigation of Truk atoll, friendly aircraft came uncomfortably close to misidentifying his ships as enemy and attacking them. On one occasion, an over-anxious gun crew in the Iowa mistakenly shot down a friendly bomber.¹⁶

As the U.S. air attacks against Truk were beginning, the Japanese command engaged in repeated attempts to locate the U.S. carriers. Eight Jill torpedo bombers took off from Param at 0545, 17 February, and spotted a group of U.S. carriers an hour later. Shortly after 0800, they found a second U.S. carrier force. An attack by torpedo bombers on the U.S. ships was planned for dusk, and orders to that effect were issued by radio to the 26th Air Flotilla on Truk. By that time, aircraft and airfield complexes had sustained enormous damage, with some aircraft having already flown out to the Marianas. Six apparently took off from Moen at 1815 to attack the carriers; though they located the task force, they scored no hits, and four of the planes were lost (at least two of them for lack of fuel). Other Japanese aircraft, however, had greater success. At 1516 three planes of Air Group 755 took off from Tinian. One of the aircraft likely was a Betty, which at about midnight succeeded in launching a torpedo at the Intrepid.¹⁷ As the carrier took evasive action, the torpedo struck the ship at her starboard quarter, jamming the rudder and flooding the steering engine room. Though badly damaged, the Intrepid still could steer with her propellers, and the decision was made immediately to detach the ship from formation and send her back to Majuro. At 0100 on 18 February,

Task Unit 58.2.4 formed to escort the Intrepid. It consisted of the light carrier Cabot (CVL-28), the cruisers San Francisco (CA-38) and Wichita (CA-45), and four destroyers. The Intrepid eventually had to be withdrawn all the way to San Francisco for repairs. Her casualties from the torpedo were 11 killed and 17 wounded.

The Japanese were not alone in carrying out aggressive operations during the night of 17-18 February. For the first time in U.S. naval history, a carrier had launched a night bombing attack against shipping. The Enterprise’s Torpedo Squadron 10 had been specially equipped with TBF-1C Avengers, each carrying four 500-pound general-purpose bombs. Launch occurred at 0207 18 February. Under the command of Lieutenant Van V. Eason, U.S. Naval Reserve, 12 blacked-out Avengers flew more than 100 miles to attack the shipping off Dublon and Eten. The Japanese detected the planes as they crossed Tmk’s reef, largely because of their ineffective exhaust-fire dampeners and the fact that a Japanese hospital ship in the lagoon switched on her lights to warn of their approach. Nevertheless, the aircraft were able to remain in the target area for 40 minutes, making radar-guided bombing runs at an altitude of 250 feet and a speed of 180 knots. Thirteen direct hits and seven near misses on shipping were recorded, with at least eight ships destroyed. One Avenger was lost to ground fire and seven were damaged. This night attack was responsible for about one-third of the total damage to shipping achieved by the entire carrier force during the operation.¹⁸

At dawn, 18 February, the large-scale assault on Truk resumed, without the Intrepid and the Cabot. Though the plan called for a second full day of operations, the supply of suitable targets was rapidly decreasing. Most of the ships in the lagoon had already been sunk or had escaped. Attacks on shore installations were stepped up, with airfields, ammunition dumps, and oil-storage tanks representing the most important targets. The day’s initial fighter sweep revealed not a single Japanese plane airborne, in great contrast with the previous day’s furious early activity. Antiaircraft fire, however, continued to be intense, especially over Dublon. On the Enterprise’s second strike on the 18th, Dauntlesses and Avengers attacked the destroyer Tachikaze, which had run aground on the reef on 4 February. The U.S. aircraft had paid little attention to the Tachikaze on the first day of action, and at daybreak the destroyer remained afloat and undamaged. But the Enterprise’s bombers did not allow that condition to last, scoring three hits and sinking the ship at 0900. She was a major warship prize of the second day’s action.

The last U.S. plane departed Truk by 1030, the recovery of aircraft was complete little more than an hour later, and Mitscher gave the order for a general retirement at 1200. The Japanese sent aircraft from Saipan late in the morning and during the afternoon in a vain effort to relocate the task force. After a brief stop at Majuro, Spruance and Mitscher proceeded northward and launched attacks against the Marianas a few days after the completion of Hailstone.

This first operation against Truk had been a great success by any measure. Disappointment among Navy air crews ran high at the time, however, because the Combined Fleet’s larger combatants were absent. Yet the damage wrought at Truk was tremendous: 10 Imperial Navy warships and 31 transports and fleet auxiliaries were sunk (a total of 200,000 tons), and at least 9 other ships were damaged. Of the 365 aircraft present on Truk at the beginning of the operation, some 70 had been shot down and another 200 destroyed on the ground. Bombers destroyed 90% of Truk’s fuel oil supply and rendered all airfield runways temporarily inoperable. Workshops and headquarters facilities had been wrecked, and some 2,000 tons of provisions were incinerated or damaged beyond use. Approximately 600 Japanese on Truk were dead or wounded; a far greater number had gone down with their ships.¹⁹

The U.S. aircraft had expended 400 tons of bombs and torpedoes on shipping and an additional 94 tons against shore installations and airfields. Aircraft flew some 1,250 combat sorties in the two-day operation.²⁰ U.S. casualties included 29 aircrewmen killed or missing, plus the casualties on the Intrepid. Some 12 U.S. fighters, 7 torpedo bombers, and 6 dive bombers were lost, though nearly one- third of these were operational accidents.²¹ Many of the surviving U.S. aircraft had, however, sustained significant battle damage. The Enterprise’s VT-10 aircraft action report notes that all of the squadron’s Avengers suffered antiaircraft artillery damage, and one plane was shot up so badly by a Zeke that it had to be pushed over the carrier’s side.²²

Other Pacific combat zones immediately felt Operation Hailstone’s wrath. The simultaneous seizure of Eniwetok went off without interference from Truk’s aircraft. Moreover, the loss of so many in-transit fighters on the ground at Truk severely hampered Rabaul’s defense from air attack. The raids of 17-18 February rendered Truk unsuitable for further use as a fleet anchorage, though it would take an additional carrier operation at the end of April and sporadic high-level raids by Army Air Forces bombers there after to neutralize Truk’s longer-term capacity for air operations. Operation Hailstone dealt Japanese morale in general a severe blow.

The operation also proved the efficacy of antishipping night attacks launched from carriers. It illustrated that fast carrier task forces could engage successfully in operations over several days against substantial land targets without support from land-based aircraft. The knowledge that carrier aviation had reached such a level maturity and effectiveness in such a short time contributed directly to the shape of the rest of the Pacific campaign. From the Marianas and the Philippines to Iwo Jima, Okinawa, and Japan itself, victory would, in no small measure, result from the dynamism and preponderance of U.S. naval air power.