by Mark Lardas
The A6M Zero dominated the first 20 months of the Pacific War. By the time the Allies were preparing to knock out Rabaul, it was past its prime, especially the A6M2, shown here. (AC)
In January 1942 Admiral Chester Nimitz, commanding naval forces in the Pacific, wanted to take the offensive at the earliest possible opportunity. Carrier raids were made against island outposts held by the Japanese at the fringes of their ocean empire in February 1942. Nimitz also deployed carrier forces in the Southwest Pacific Area as early as March 1942. US carriers stopped the Japanese from capturing Port Moresby, and materially assisted the Allied advance in the Solomons.
Nor was the desire to go on the offensive limited to the US Navy. Chased out of the Philippines, General Douglas MacArthur vowed to return. Headquartered in Australia, and commanding Allied forces in the region, he began offensive actions against the Japanese in late 1942.
MacArthur and Nimitz led the two major commands in the Pacific. Nimitz commanded the Pacific Ocean Areas, divided into the North Pacific Area (everything north of the 42nd parallel), the Central Pacific Area (between the equator and 42 degrees north, except for the area around the Philippines), and the South Pacific Area (everything south of the equator and east of latitude 159 east). MacArthur controlled the Southwest Pacific Area, which included Australia, New Guinea, the Dutch East Indies east of Sumatra, the Philippines and the waters around them. East of New Guinea the northern boundary ran along the equator to 159 degrees east. New Britain, New Ireland, and Rabaul fell within the boundaries of the Southwest Pacific Area, with the Solomons split between the South Pacific Area and the Southwest Pacific Area.
Nimitz assigned a deputy to run the South Pacific Area. By 1943, Admiral William Halsey, an aggressive leader, who revitalized the stalled US effort to secure Guadalcanal, was in charge. The boundary between the South Pacific Area and Southwest Pacific Area required cooperation between Halsey and MacArthur. Halsey’s forces could penetrate into MacArthur’s sphere with the permission of MacArthur. MacArthur, focused on retaking the Philippines, willingly worked with Halsey to defeat Rabaul.
For the Japanese, Rabaul was in their Southeast Area. The Southeast Area’s western boundary was 140 east longitude, cutting through the middle of New Guinea. Its northern boundary was just above 1 degree north, on a line between Kapingamarangi and Nauru. From east of Nauru it ran southeast between the Fijis and Samoas, and then south. Rabaul was near the top of the region, roughly in its middle. This was a joint Imperial Japanese Army and Navy command. The land forces were commanded by General Hitoshi Imamura, while the Southeast Area’s naval leader was Vice Admiral Jinichi Kusaka. In a rare example of inter-service harmony, the two leaders cooperated closely.
General Hitoshi Imamura commanded the Imperial Japanese Army forces within Japan’s Southeast Area, headquartered at Rabaul. He remained after New Britain was cut off, as senior Japanese officer surrendering Rabaul at war’s end. (USNHHC)
Planning begins
The Allies’ first serious plan to take Rabaul was drafted in July 1942. The Joint Chiefs of Staff of the US Armed Forces sent a directive to the South and Southwest Pacific Area commanders to begin an advance against Rabaul. The directive was divided into three tasks. Task One directed the seizure of Guadalcanal, Tulagi, and the Santa Cruz Islands. Task Two called for recapturing the remaining Solomon Islands and northeastern coast of New Guinea. This included Japanese-held Lae, Salamaua, and points north. Task Three called for the occupation of New Britain, including Rabaul. Landings on Guadalcanal and Tulagi (occupation of the Santa Cruz Islands proved unnecessary), were scheduled for August 1942, but no deadlines were set.
In January 1943 the Casablanca Conference was held, defining Allied strategic objectives for the war. This meeting of the President of the United States, the Prime Minister of Great Britain, and the Combined Chiefs of Staff of both nations set the outline for the war. Defeating Germany and aiding the Soviet Union were given priority. A bomber offensive against Germany would start by mid-summer. China was to be kept in the war by recapturing Burma and reopening a supply road to China. The Allies were to maintain the offensive against the Japanese in the Southwest Pacific, including the recapture of Rabaul, but only resources unneeded elsewhere would be sent to the Southwest Pacific.
By February 1943, Task One goals had been achieved. MacArthur’s staff drew up a plan, called Elkton, to complete Task Two and Task Three of the Joint Chiefs’ objectives. It broke the tasks into five operations:
1.Seizing airfields on New Guinea’s Huon Peninsula to provide bases for operations against Rabaul.
2.Seizing New Georgia and the new Japanese airfield on Munda Point to cover operations in the Northern Solomons.
3.Seizing airfields on Bougainville and New Britain outside the Gazelle Peninsula to support operations against Rabaul and Kavieng.
4.Capturing Kavieng to isolate Rabaul.
5.Capturing Rabaul.
This plan was discussed with Halsey. He agreed to support it. However, what had been learned at Guadalcanal and New Guinea was that removing Japanese land garrisons required commitments of large numbers of Allied troops and a significant expenditure of time and resources. When Elkton was reviewed in Washington the Joint Chiefs decided the resources needed to capture Rabaul were unavailable. Providing the required aircraft, especially heavy bombers, would cut into the bomber offensive against Germany. Several divisions of trained troops were available in the United States, but insufficient transports were available to move the units to the Southwest Pacific and supply them once there. Few naval reinforcements could be provided, especially aircraft carriers. Prewar construction had been whittled down to two fleet carriers, and new construction was needed for a planned offensive in the Central Pacific. Any offensive against Rabaul would largely rely on assets already in the theater. Reinforcements would be limited to replacements for losses.
Henderson Field, Guadalcanal in August 1942. Henderson Field served mainly as a base for heavy bombers during the aerial siege of Rabaul. (USNHHC)
Elkton was re-written in late February, and a new plan presented to the Joint Chiefs in March. Elkton II was predicated on capturing airfields. The intention was to move airpower ever closer to Rabaul, isolating it before invading. Once Rabaul was ringed by airfields, so no reinforcements or supplies could reach it, ground troops could land, taking the city and harbor.
But even Rabaul isolated would be a tough nut to crack. Any Allied invasion force faced a force of nearly 100,000 men. This included an Imperial Japanese Army garrison of two infantry divisions, two infantry brigades, an artillery brigade, and an armor brigade. The Navy could contribute four naval guard units and a special naval landing unit, each equivalent to regimental strength.
In March 1943, including New Zealand, Australian, and US troops, the South and Southwest Pacific Areas had only the equivalent of 16 divisions available. Only six were combat ready. The rest were training or only suitable for garrison duty. Given commitments in New Guinea, and the troops required elsewhere in the theater, there were insufficient troops available to invade, much less take Rabaul.
However Elkton II suggested a solution, underscored by the results of the battle of the Bismarck Sea, where airpower alone stopped the Japanese reinforcing New Guinea. The solution was put forward in a further development, Elkton III: simply skip the invasion of Rabaul. Rabaul and its magnificent harbor were well-placed to support a Japanese invasion of Australia, but ill-positioned to support Allied operations to recapture the Philippines or take the Marianas. The Admiralties, north and west of Rabaul, offered a better location for a move to the Philippines and an adequate harbor, and would need to be taken in order to ring Rabaul.
Instead of Rabaul being occupied, it would be isolated and shorn of its airpower, and then could be largely ignored. Due to the mountainous terrain on New Britain, the Japanese garrison could not leave the Gazelle Peninsula, and the artillery and tanks there would have no influence beyond the range of their shells – pe
rhaps 5 miles from the coast. A bypassed Rabaul would serve as an open-air internment camp for a major segment of the Japanese Pacific army, although Allied air raids would continue to weaken the garrison, guarantee air superiority, and prevent any rebuilding. Better still, as the Imperial Japanese were certainly not going to surrender, this internment camp would be self-run, and not draw on limited Allied logistics the way housing and feeding 100,000 prisoners of war would.
Preliminary conquests
The Huon Peninsula and New Georgia would still be taken, although Allied troops would still face off against entrenched Japanese ground forces. Control of the Huon Peninsula was needed not just as a springboard to Rabaul, but to secure Port Moresby and also the Vitiaz and Dampier Straits. These were needed for the march to the Philippines. The Japanese airbase at Munda on New Georgia threatened Guadalcanal and (if held by the Allies) permitted fighter cover as far north as Bougainville, another stepping stone to Rabaul.
Those were the only fortified positions to be taken, however. The rest of the plan called for seizing lightly defended islands circling New Britain and New Ireland where airfields could be built. A landing would be made, the island secured, and an airfield placed. Each island would be within fighter range of Allied air bases, allowing air cover while the airfield was under construction. Each new landing was closer to Rabaul, until single-engine Allied aircraft could reach that fortress. Landings would also be made on western and central New Britain, capturing Japanese airfields there. These were lightly garrisoned.
The most original part of the plan involved Bougainville. Geography and logistics dictated an Allied airfield on Bougainville. The Japanese had several airfields on the north and south ends of the island, as well as on Buka. These were heavily garrisoned. The Allied plan bypassed these. Instead, US Marines would land in the lightly held center of the island, establish a perimeter, and build airfields within that perimeter. The perimeter would be large enough to place the airfields outside the range of Japanese artillery, but no larger. Once established, Allied forces would entrench, and let the Japanese bleed trying to penetrate jungle fortifications.
The plan was risky because Bougainville was within easy range of Japanese fighters stationed around Rabaul and Japanese warships anchored at Simpson Harbor. The invasion fleet was gambling the US Navy could best the Imperial Japanese Navy’s warships in surface night engagements, warfare at which the Japanese excelled. The odds against the Allies were increased because the heaviest available Allied surface units were light cruisers armed with 6in batteries, while the Japanese had several heavy cruisers packing both 8in batteries and Long Lance torpedoes. The rest of the Allied fleet, its fleet carriers, battleships, and heavy cruisers, were committed to the Central Pacific Area.
In order to reduce Rabaul, once other threats in the theater had been suppressed (most notably Japanese air assets in New Guinea and the Solomons) a concentrated air campaign would be turned against Rabaul. The five airfields around Rabaul and ships in Simpson Harbor and Blanche Bay were to be targeted first. Weather permitting, daily raids were to be conducted against the airfields and harbors. Runways were to be cratered, service buildings flattened, and aircraft destroyed. Ships would be sunk, wharves and loading facilities destroyed, and warehouses bombed. Accompanying Allied fighters would engage Japanese fighters.
Dobodura was the first Allied airfield east of New Guinea’s Owen Stanley mountain range. It shortened the flying distance to Rabaul and allowed aircraft to avoid a climb over the Owen Stanley Mountains while fully loaded. (USAAF)
Allied intelligence estimated the Japanese had 290 aircraft at Rabaul. The Japanese actually had 300 naval aircraft, reinforced by a monthly allotment of 50 aircraft. They could also call in another 200–300 from the Combined Fleet. Yet the Allies had a total of 1,800 aircraft in the area (including transports) and were building inventory. Given an ongoing campaign, Japan would eventually run out of fighters. Once this happened, Allied airpower would turn its attention to infrastructure, destroying warehouses, supply dumps and fuel depots, repair facilities, communications centers, barracks, and headquarters.
The plan was delivered by General George Kenney, MacArthur’s air commander. He had been fighting Rabaul since his arrival in July 1942. The Joint Chiefs approved, and the plan was implemented as Operation Cartwheel. It took time to grind through the initial stages – seizing the Woodlark Islands and Kiriwina, securing New Georgia, clearing the Huon Peninsula, and obtaining air superiority in New Guinea. By October 1943, these had been done.
The ungainly PBY Catalina played an important offstage role during the siege of Rabaul. Black Cat Catalinas flew night missions against Japanese shipping and naval warships. Dumbo Catalinas rescued Allied flyers downed in the waters off New Britain and New Ireland. (AC)
THE RABAUL THEATER: OCTOBER 1943–MAY 1944
1.October 12-November 5: Fifth Air Force launches three weeks of intensive airstrikes against Rabaul.
2.November 1: Allies land on Bougainville.
3.November 5: Carrier strike against Rabaul from Saratoga and Princeton.
November 11: Carrier strike against Rabaul.
4.November 25: Carrier airstrikes on Kavieng
5.December 10: Torokino airfield operational.
6.December 15: Aware invaded.
7.December 17: First fighter sweep over Rabaul.
8.December 26: Cape Gloucester invaded.
9.January 1944-April 1944: ComAirSols launches intensive airstrikes against Rabaul and its airfields.
10.January 10: Piva airfield operational
11.February 15: Green Islands invaded, airfield on Nissan Airfield operational March 8.
12.February 18: Kavieng’s airfields neutralized by airstrikes.
13.February 22-29: Rabaul bombarded by sea.
14.February 29: Manus invaded by Allies; airfield operational by April.
15.March 20: Marines invade Emirau, Airfield operational by April 11.
Japanese air bases
A.Rabaul complex (Lakanai, Vunakanau, Tobera, Rapopo, Keravat) (bomber)
B.Kavieng (bomber)
C.Buka (fighter), lost November 1943
D.Kara/Kahili (fighter), lost November 1943
E.Aware (fighter), lost December 1943
F.Cape Gloucester (fighter), lost December 1943
G.Talasea (fighter), lost January 1943
H.Gatsama (fighter), lost February 1943
I.Namatanai Airfield (fighter)
J.Borpop Airfield (fighter)
Allied air bases
A.Port Moresby (bomber)
B.Henderson Field (bomber)
C.Dobodura (bomber)
D.Kiriwina Island (fighter)
E.Woodlark Island (fighter)
F.Tsili-Tsili (bomber)
G.Munda (bomber)
H.Barakoma, Vella Lavella (fighter)
I.Torokina, Bougainville (fighter), December 1943
J.Piva, Bougainville (bomber), January 1944
K.Green Is (fighter), March 1944
L.Emirau (bomber), May 1944
M.Manus, Admiralty Islands (bomber), June 1944
N.Finschaven (bomber)
O.Cape Gloucester (fighter), January 1944
P.Talasea (fighter), May 1944
Q.Gasmata (fighter), May 1944
R.Aware (fighter), January 1944
Allied air bases
Allied naval ports
Japanese air bases
Japanese naval ports
Allied Lines, October 1, 1943
Allied Lines, January 1, 1944
Allied Lines, April 1, 1944
Allied Lines, July 1, 1944
Bomber ranges
Fighter ranges
THE CAMPAIGN
Slowly tightening the noose
First air operations: 1942–43
Although plans for the reduction of Rabaul were finalized in April 1943, it was six months before the air campaign against Rabaul started in earnest. In April only the Fif
th Air Force, based in New Guinea, could reach Rabaul with fighter aircraft, its P-38s. The Fifth Air Force had mounted its first air attack against Rabaul in October 1942. It intermittently raided Rabaul and its airfields over the next eight months, but took these off its targeting list after June 1943. Too many other things took priority between mid-June and October. Late June and July were spent supporting the invasions of the Woodlarks and Kiriwina. August was consumed with reducing Wewak, Rabaul’s aerial counterpart on New Guinea, and September saw the Fifth Air Force supporting the invasions of Lae and Finschhafen. Although necessary precursors to a Rabaul campaign, these operations forced the Fifth Air Force to neglect Rabaul.
An RAAF Beaufighter squadron participated in the first day’s attack, strafing and bombing the Japanese airfield at Tobera. This picture shows an RAAF Beaufighter flying past New Guinea’s Owen Stanley Mountains. (AC)
The attention of Comairsols was consumed with operations in the Solomons. Spring saw invasions of the Russells. Summer was spent planning and executing the New Georgia invasion (culminating with the capture of the airfield at Munda). Fall saw planning and preparations for the invasion of Bougainville, scheduled for November 1. These activities absorbed all air resources in the Solomons, forcing Comairsols to ignore Rabaul.
As September ended, the Fifth Air Force completed priority activities in New Guinea and western New Britain. George Kenney was eager to revisit Rabaul. He viewed Wewak as a rehearsal for the big show at Rabaul. Taking Rabaul down a peg or two before the Bougainville landings would keep the Japanese off the backs of the invaders. Kenney also knew Bougainville airfields would bring Comairsols closer to Rabaul than the Fifth Air Force. If the Fifth Air Force were to knock out Rabaul before Bougainville’s airfields came on line it had to act. Kenney believed one month’s steady bombing would be enough.