Two Birds with One Hailstone

By Alan P. Rems

Target Rabaul

General Douglas MacArthur’s offensive plan in the South Pacific involved surrounding Rabaul in 1943 and early 1944 followed by invasion later. That changed in August 1943 when Allied military leaders decided at the Quebec Conference to bypass Rabaul. They also approved, in concept, Admiral Chester A. Nimitz’s plans for a Central Pacific offensive, with Truk one of many possible objectives.

Always concerned about diverting resources from the war in Europe, the British delegation questioned the need for two separate Pacific lines of attack. The value of that strategy would be demonstrated when the Central Pacific offensive opened in the Gilbert Islands in November 1943. While enemy ground troops fought fanatically on Tarawa, there was little response from the air because Japanese air power had been badly depleted in the South Pacific. That favor would be repaid in full by Nimitz three months later.

Before the start of the Central Pacific offensive, on 1 November, South Pacific Area commander Admiral William F. Halsey Jr. had landed forces on Bougainville. From airstrips there and elsewhere in the Solomons, American Army, Navy, and Marine and Royal New Zealand Air Force planes—the polyglot Air Solomons (AirSols) team—brought Rabaul under attack.

After a slow start in December, newly developed AirSols bases made heavier attacks in the New Year possible. Japanese forces resisted fiercely, bringing down 33 AirSols aircraft during one week in January 1944. A noted casualty that month was colorful air ace Major Gregory “Pappy” Boyington, commander of “Black Sheep” Marine Fighter Squadron 214. Shot down over Rabaul, Boyington was fished from the water by a Japanese submarine and brought there.

Although enemy losses were far heavier than AirSols’, the Japanese readily obtained replacement aircraft through a supply line that extended from Japan to Truk, from which aircraft were ferried to Rabaul by way of Kavieng, New Ireland. After freshly trained naval pilots and their planes arrived from Singapore, Rabaul’s air strength in January numbered about 300 planes.

AirSols’ bombings continued unabated in February, climaxing in a massive raid on the 19th of that month. Two of Rabaul’s four surrounding airstrips were heavily damaged and a dozen of the 50 defending Japanese fighters were downed. It would be the last significant air battle over Rabaul. Abruptly, events in the Central Pacific forced the Japanese to abandon the skies of the South Pacific.

Operation Hailstone

After the Gilberts fell, Nimitz prepared to move against the Marshall Islands. Convinced of the continued weakness of Japanese air power in the Central Pacific, the Pacific Fleet commander-in-chief brushed aside the fears of his principal commanders who favored a more cautious approach and aimed for the center of the enemy position—Kwajalein Atoll. Nimitz was proved correct when Kwajalein fell with remarkable ease.

To maintain momentum, it was decided to accelerate the planned invasion of Eniwetok Atoll, which was wanted as a staging base for advances into the Caroline and Mariana islands. With Truk situated 700 miles from Eniwetok, the vaunted Japanese base needed to be suppressed to prevent intervention.

Truk consisted of an enormous coral reef surrounding six principal islands and many islets, “a drowned mountain range inside a coral ring” as described by historian Samuel Eliot Morison. The reef was pierced by four openings covered by coastal defense guns. Hidden from world view, Truk had developed a reputation of nearly insurmountable strength. One air group commander would say, doubtless rhetorically, that his first impulse on learning the target was to jump overboard.

Fear of the unknown had magnified the threat, as Truk’s reputation was greatly overblown. Only 10,000 to 12,000 Japanese soldiers and sailors garrisoned the atoll; also, Truk had just 40 antiaircraft guns, all of which lacked radar. But there was no shortage of aircraft. At the time of the raid, about 160 planes were ready for immediate employment with another 180 ready for delivery to Rabaul and elsewhere.

The Truk raid, Operation Hailstone, would be conducted by the fast carriers of the U.S. 5th Fleet commanded by Vice Admiral Raymond A. Spruance, the victor at Midway. In January 1944, only weeks before the operation, Rear Admiral Marc A. Mitscher assumed command of the carriers, replacing Rear Admiral Charles A. Pownall, whose conduct of operations in the Marshalls was considered insufficiently aggressive by Nimitz’s headquarters. Having grown up with naval aviation from its earliest days with service on board the Navy’s first carrier, the Langley (CV-1), Mitscher enjoyed unequaled respect from the carrier commanders. They particularly appreciated his style of command, which was succinctly described by Mitscher: “I tell them what I want done. Not how!”

One of the few not pleased with the change was Spruance, who thought well of Pownall and resented his removal at the instigation of Vice Admiral John H. Towers, Nimitz’s commander of naval air forces. Towers and Spruance clashed about how the carriers should be employed, with Towers’ more aggressive outlook finally prevailing. Spruance would come to fully appreciate the talents of his new commander, judged by Morison facile princeps (easily first) of America’s carrier leaders.

To develop information about Truk, two Marine PB4Y-1 Liberators flew 850 miles from Bougainville to photograph the base. Although clouds obscured the view, many warships and cargo vessels were observed in the lagoon. Admiral Mineichi Koga, successor to Admiral Isoroku Yamamoto, had already recognized Truk’s vulnerability and begun to withdraw the Combined Fleet. After the Marine planes were observed, this movement was accelerated and soon completed, with Koga himself departing with part of the fleet to Japan.

Spruance’s 5th Fleet included 12 carriers organized in four carrier groups. Expecting no important naval opposition at Eniwetok, just one carrier group was sent there. The other three groups, organized as Task Force (TF) 58, centered on five heavy carriers and four light carriers, headed for Truk. Hoping to engage Japanese vessels fleeing the lagoon, Spruance transferred his flag to the battleship New Jersey (BB-62) in preparation for a surface action. Since that hardly seemed necessary, Spruance’s chief of staff wondered if his commander was essentially on a sightseeing trip, curious to see the base that had long dominated naval planning. Spruance’s biographer, Thomas B. Buell, speculated that the admiral might have wanted to flaunt American naval dominance by sailing a victory lap outside the Japanese equivalent of Pearl Harbor.

The first success was scored the day before the raid when the American submarine Skate (SS-305) spotted and sank the light cruiser Agano as she left the lagoon. A Japanese destroyer saved most of the Agano ’s crew, but nearly all of them would perish during the raid when their rescuer was sunk.

Sailing undetected to a point 90 miles east-northeast of Truk, TF 58 launched 72 F6F Hellcat fighters that arrived over Truk at 0800 on 17 February. Mitscher’s strategy called for the Hellcats to fully engage the enemy fighters and soften up the ground defenses, clearing the way for the bombers. That idea worked perfectly, as 30 of the 80 A6M Zeros that rose were downed against the loss of just four Hellcats. After brushing the air opposition aside, the F6Fs headed for three principal airfields where they destroyed about 40 planes. On the heels of the Hellcats, 18 TBF Avengers dropped incendiaries on the airfields.

One witness to the destruction was Pappy Boyington, en route from Rabaul to captivity in Japan. Landing on Truk at the start of the attack, Boyington was hustled into a concrete slit trench as a Hellcat destroyed the aircraft in which he arrived.

With Truk softened up, the attack on shipping began. Although the Combined Fleet was gone, the lagoon was crowded with ripe targets. Present were about 50 cargo ships and auxiliaries, delayed there because of weather, plus many naval escorts including 3 light cruisers and 8 destroyers. Mitscher’s fighters, dive bombers, and torpedo bombers carried out 30 strikes, each more powerful than at Pearl Harbor. Air opposition was minor and sporadic, the only substantial resistance coming from antiaircraft fire.

When he received news that enemy ships were fleeing the lagoon, Spruance formed a task group centered on the New Jersey and Iowa (BB-61). With the admiral in tactical command, the ships circled Truk in search of prey, but with results that were hardly commensurate with the risks. A crippled cruiser and destroyer were dispatched, and two smaller naval vessels were engaged and sunk. In the process, a Japanese bomb nearly hit the Iowa and torpedoes fired by the crippled destroyer straddled the New Jersey . Although an essentially cautious commander, Spruance was anything but that in needlessly exposing his capital ships at Truk.

That evening, the Japanese sent six radar-equipped B5N Kate torpedo planes against Mitscher’s carriers. After being held off for about two hours, one Kate eluded the night fighter defense to deliver a torpedo that struck the Intrepid (CV-11). Eleven crewmen were killed and 17 wounded by the hit, which flooded several compartments and jammed the carrier’s rudder. Withdrawing to Eniwetok under her own power, the Intrepid would be sidelined for several months.

Meanwhile, above the lagoon, 12 radar-equipped TBF-1C Avengers conducted the first nighttime bombing of shipping by U.S. carrier aircraft. Able to locate enemy ships in the darkness, the Avengers made 25 runs at masthead level, scoring 13 direct hits.

The onslaught continued after daylight. With light antiaircraft fire now the only opposition, attacks primarily were directed against airstrips, hangars, storage tanks, and ammunition dumps. Then, with Mitscher and Spruance concerned that the Japanese might repeat their success against the Intrepid if the warships remained after dark, TF 58 departed at noon on 18 February.

Spruance’s raid cost 12 fighters, 7 torpedo bombers, and 6 dive bombers, most lost to antiaircraft fire, plus the Intrepid ’s damage and casualties. Twenty-two downed airmen were rescued thanks to efficient lifesaving efforts by submarines, destroyers, and aircraft. The price was minuscule in relation to the results.

Sixteen Japanese naval vessels were sunk, including 3 light cruisers, 4 destroyers, and 9 auxiliary vessels; in addition, 19 cargo marus and 5 tankers were destroyed. In all, Japan lost nearly 200,000 tons of badly needed shipping. Still, Morison believed that with air opposition essentially absent the score should have been higher. He traced the problem to overemphasis during pilot training on aircraft interception and amphibious support with too little attention to vessel attacks.

Of greatest consequence was the toll on Japanese aircraft. More than 250 planes were destroyed or damaged, leaving fewer than 100 intact. With his air defenses shattered, Koga recognized that he lacked the strength to defend the Central Pacific while the attrition of aircraft continued at Rabaul. Two days after Hailstorm, the Combined Fleet commander ordered his aircraft in the South Pacific to leave for Truk.

‘Plaster Truk with Everything . . . Including Beer Bottles’

At the time of the February raid, the Allies were undecided if Truk would be invaded later. Based on the raid’s success, the Joint Chiefs of Staff decided the atoll could be bypassed safely. However, situated on the flank of Allied operations in the Marianas, New Guinea, and the Palaus, and with the ability to bring in fresh aircraft, it was essential to keep Truk neutralized. That job fell to the B-24 heavy bombers of the Army’s 13th Air Force, flying from Solomon bases, and 7th Air Force, operating from the Marshalls in the Central Pacific.

As Truk nevertheless remained a threat, Nimitz was anxious to hit it with another carrier raid. In late April that opportunity presented itself when Spruance’s carriers returned to the Central Pacific after supporting MacArthur’s great leap along the New Guinea coast to Hollandia. As the carriers prepared for a return visit to Truk, Mitscher, whose hatred of the enemy knew no bounds, signaled: “Plaster Truk with everything you have including empty beer bottles if you have any.”

The morning of 29 April, at a range of 150 miles, 84 Hellcats embarked on a fighter sweep of the atoll. With ample radar warning, 62 Zeros lay in wait but were quickly eliminated by the raiders. Meanwhile, Japanese torpedo planes found the carriers but were repelled by the fighter cover and ship antiaircraft fire. During TF 58’s two-day attack, of the 105 Japanese planes at Truk, 59 were shot down and 34 were destroyed on the ground; also, nearly all land structures were destroyed. A few small craft were found and promptly sunk in the lagoon, including fishing boats used to catch food for the isolated garrison.

Mitscher lost 26 planes in combat, most again from antiaircraft fire. However, rescue techniques once more worked so well that most of the downed airmen were recovered.

Left with only 12 operational aircraft, Truk for the while was thoroughly neutralized. When the Marianas campaign commenced in June, the few surviving planes were flown to Guam. The Japanese thereafter gave up trying to maintain Truk as a principal base. Only seven supply submarines got through to deliver supplies over the remaining course of the war.

‘Kicking Around a Corpse’

Even without aircraft, with a superbly developed infrastructure, massive antiaircraft defenses, and a large garrison, Rabaul could not be ignored. During the three months after Japanese aircraft were withdrawn, AirSols dropped 7,410 tons of bombs on the town, the surrounding airfields, and the small barges and ships that ventured into Simpson Harbor. Beginning in March, fighter planes equipped with bomb racks flew there on unescorted bombing “milk runs.”

Rabaul’s encirclement was completed during February and March 1944. While MacArthur’s forces occupied the Admiralty Islands, Halsey took the Green Islands and Emirau, from which Allied aircraft closed down Kavieng, Rabaul’s link to Truk. To historian Eric M. Bergerud, the Japanese defeat in the South Pacific was even more consequential than El Alamein and Sicily for the Germans. In its long-term impact, Bergerud considered its importance comparable to Stalingrad.

With the South Pacific won, Halsey’s command was dissolved; all Allied forces in the area including AirSols were assigned to MacArthur. Before the changeover, AirSols’ commander tried to obtain more useful work for his airmen then the repeated bombing of Rabaul, which he regarded as “kicking around a corpse.” For most of the fliers who remained in the South Pacific, that was indeed their fate.

Unlike Rabaul, where Allied fighter and bomber bases were nearby, long over-water bomber flights were required to keep Truk neutralized. An Air Force evaluation board described the problem: “It is a matter of hours or at most a day or two to repair runways such as the Japs use; to rebuild light frame buildings; and to fly replacement airplanes down through the chain of the mandated islands.” Particular attention was devoted to Truk during the invasion of the Marianas in June 1944, when bombings reached their peak of 1,813 tons.

Truk in enemy hands had some educational value. During the autumn of 1944, newly arrived B-29 Superfortresses practiced there in safety. At their customary bombing altitudes, the B-29s were immune from antiaircraft fire and the few Japanese fighters that sometimes appeared, suffering no losses in 32 missions. Later, in mid-1945, Truk was used to introduce a British task group to the Pacific war. Over two days and nights, the heavy carrier HMS Implacable with her accompanying cruisers and destroyers pummeled what little remained of the atoll at the cost of one aircraft downed by antiaircraft fire.

After June 1944, when the 13th Air Force was assigned other duties, the 7th Air Force took on full responsibility for Truk. Like the aviators looking after Rabaul, they found it a thankless, monotonous task. At the war’s end, the Strategic Bombing Survey concluded: “attacks on Rabaul and other by-passed positions were continued longer and in greater volume than required.” Those who were there doubtless agreed.

Truk and Rabaul remained in enemy hands up to the surrender of Japan. Reflecting on the vast resources poured into the development of Rabaul, Morison noted “the folly of building up a great overseas base and garrison without a navy capable of controlling the surrounding waters and air.” While somewhat less was invested in facilities and manpower at Truk, Morison’s essential point applied there as well. Torn between its need to support both bases, Japan lacked the power to maintain either one.

Historians will probably never agree whether a concentrated thrust in the Pacific could have obtained better results than the dual drive by the Allies in the South and Central Pacific. Yet there is no question that the approach sometimes yielded considerable benefits, never more so than when two of Japan’s most precious “birds” were unseated by one “Hailstone.”


Eric M. Bergerud, Fire in the Sky: The Air War in the South Pacific (Boulder, CO: Westview Press, 2000).

Thomas B. Buell, The Quiet Warrier: A Biography of Admiral Raymond A. Spruance (Boston: Little, Brown and Company, 1974).

Wesley F. Craven and James L. Cate, eds., The Army Air Forces in World War II , vol. 4, The Pacific: Guadalcanal to Saipan August 1942 to July 1944 ; vol. 5, The Pacific: Matterhorn to Nagasaki June 1944 to August 1945 (Chicago: University of Chicago Press, 1950, 1953).

Paul S. Dull, A Battle History of the Imperial Japanese Navy 1941–1945 (Annapolis, MD: Naval Institute Press, 1978).

Samuel Eliot Morison, History of United States Naval Operations in World War II , vol. 7, Aleutians, Gilberts and Marshalls June 1942–April 1944 ; vol. 8, New Guinea and the Marianas, March 1944–August 1944 (Boston, MA: Little, Brown and Company, 1951, 1953).

Louis Morton, The United States Army in World War II, The War in the Pacific, Strategy and Command: The First Two Years (Washington, DC: Office of the Chief of Military History, Department of the Army, 1962).

John Prados, Combined Fleet Decoded (New York: Random House, 1995).

Clark G. Reynolds, The Fast Carriers: The Forging of an Air Navy (Annapolis, MD: Naval Institute Press, 1992).

Robert Sherrod, History of Marine Corps Aviation in World War II (Washington, DC: Combat Forces Press, 1952).

Theodore Taylor, The Magnificent Mitscher (New York: W. W. Norton & Company, 1954).



Conferences and Events

WEST 2019

Wed, 2019-02-13 - Fri, 2019-02-15

Sharpening the Competitive Edge: Are We Ready to Compete, Deter, and Win Globally? Wednesday, 13 February - Friday, 15 February...

2019 U.S. Naval Institute Member Event

View All

From the Press

19 January - Book Fair

Sat, 2019-01-19

23 January - Book Talk

Wed, 2019-01-23

Why Become a Member of the U.S. Naval Institute?

As an independent forum for over 140 years, the Naval Institute has been nurturing creative thinkers who responsibly raise their voices on matters relating to national defense.

Become a Member Renew Membership