Bougainville Campaign

Bougainville Campaign (1943–45)
Part of the Pacific Theatre of World War II
United States Army soldiers hunt Japanese infiltrators on Bougainville in March 1944.
Date 1 November 1943 – 21 August 1945 Location 6°8′S 155°18′E / 6.133°S 155.300°E / -6.133; 155.300Coordinates: 6°8′S 155°18′E / 6.133°S 155.300°E / -6.133; 155.300 Bougainville, Territory of New Guinea (geographically part of the Solomon Islands) Result Allied victory
Belligerents
United States  Australia  New Zealand Colony of Fiji	Empire of Japan
Commanders and leaders
Douglas MacArthur William F. Halsey Theodore S.        Wilkinson Alexander A.        Vandegrift R. A. Row Allen H. Turnage Robert S. Beightler Roy S. Geiger Oscar W. Griswold H. E. Barrowclough Thomas Blamey Stanley Savige	Hitoshi Imamura Harukichi Hyakutake Mineichi Koga Jinichi Kusaka Tomoshige        Samejima Sentaro Omori Kiyoto Kagawa † Masatane Kanda
Strength
144,000 American troops 30,000 Australian troops[1] 728 aircraft[2]	45,000–65,000 troops[3] 154 aircraft[2]
Casualties and losses
USA: 727 dead Australia: 516 dead[4]	18,500–21,500 dead[5][Note 1]

Bougainville Campaign Land 1943 Cape Torokina Landings Koromokina Piva Trail Coconut Grove Piva Forks Koiari Raid Naval 1943 Empress Augusta Bay Cape St. George Land 1944 Hellzapoppin Ridge & Hill 600A Japanese Counterattack Pearl Ridge Land 1945 Tsimba Ridge Slater's Knoll Hongorai River Porton Plantation Ratsua

Solomon Islands campaign Southern Solomons Japanese Invasion of Tulagi Guadalcanal Campaign Operation Cartwheel Operation I-Go Operation Vengeance Central Solomons New Georgia Campaign Vella Lavella Northern Solomons Treasury Islands Raid on Choiseul Bombing of Rabaul Bougainville Campaign Green Islands

New Guinea campaign 1942 Japanese seizure of Rabaul Japanese seizure of Lae and Salamaua Coral Sea Japanese seizure of Buna–Gona Kokoda Track Milne Bay Goodenough Island Lilliput Recapture of Buna–Gona 1943 Wau Bismarck Sea I-Go Recapture of Lae and Salamaua Cartwheel Finisterres Huon Peninsula Bougainville New Britain Reduction of Rabaul 1944–45 Admiralties Emirau Take Ichi Western New Guinea Aitape–Wewak

The Bougainville Campaign (Operation Cherry Blossom) was a series of land and naval battles of the Pacific campaign of World War II between Allied forces and the Empire of Japan. It was part of Operation Cartwheel, the Allied grand strategy in the South Pacific. The campaign took place in the Northern Solomons in two phases: the first phase, in which American troops invaded and held the Perimeter around the beachhead, lasted from November 1943 through November 1944; the second phase, in which British Commonwealth troops attempted to mop up pockets of starving, isolated but still-determined Japanese, lasted from November 1944 until August 1945, when the last Japanese on the island surrendered.

Japanese occupation

Before the war, Bougainville had been administered as part of the Australian Territory of New Guinea, even though, geographically, Bougainville is part of the Solomon Islands chain. The United Kingdom and Germany had traded it for another islands territory which became British rather than German. As a result, the campaign is referred to as part of both the New Guinea and the Solomon Islands campaigns.

During their occupation the Japanese constructed naval aircraft bases in the north, east, and south of the island; but none in the west. They developed a naval anchorage at Tonolei Harbor near Buin, their largest base, on the southern coastal plain of Bougainville. On the nearby Treasury and Shortland Islands they built airfields, naval bases and anchorages. These bases helped protect Rabaul, the major Japanese garrison and naval base in Papua New Guinea, while allowing continued expansion to the south-east, down the Solomon Islands chain, to Guadalcanal.

In March–April 1942, the Japanese landed on Bougainville as part of their advance into the South Pacific. At the time, there was only a small Australian garrison on the island which consisted of about 20 soldiers from the 1st Independent Company and some coastwatchers. Shortly after the Japanese arrived, the bulk of the Australian force was evacuated by the Allies, although some of the coastwatchers remained behind to provide intelligence.^[6] Once secured, the Japanese began constructing a number of airfields across the island.^[7] The main airfields were on Buka Island, the Bonis Peninsula in the north, at Kahili and Kara, in the south, and Kieta on the east coast,^[7] while a naval anchorage was constructed at Tonolei Harbor near Buin on the southern coastal plain, along with anchorages on the Shortland Islands group.^[8]

The airfield at Kahili was known by the Japanese as Buin Airfield,^[9] and to its south was an airfield on Ballale Island in the Shortland Islands. These bases allowed the Japanese to conduct operations in the southern Solomon Islands and to attack the Allied lines of communication between the United States, Australia and the Southwest Pacific Area.^[7]

At the opening of the Allied offensives, estimates of Japanese strength on Bougainville varied widely, ranging between 45,000 to 65,000 Army, Navy, and labour personnel.^{[3][Note 2]} These forces constituted the Japanese 17th Army, commanded by General Harukichi Hyakutake.

Hyukatake reported to General Hitoshi Imamura, commander of the Japanese Eighth Area Army, headquartered at Rabaul on New Britain Island. Naval command at Rabaul was the responsibility of Vice Admiral Jinichi Kusaka, commander Southeast Area Fleet. The level of cooperation between these two officers was greater than that usually found between the branches of the Japanese armed forces.^[10]

Allied planning

Choice of Bougainville

Reduction of the main Japanese base at Rabaul was the ultimate goal of the Allied offensive in the Solomons (Operation Cartwheel). That city was already within range of Allied heavy bombers, but a closer airfield was needed for light bombers and escort fighters. Thus, the entire island of Bougainville did not need to be occupied; only enough relatively flat land to support an airbase was required. This "was the one and only reason why the JCS authorized Halsey to seize a section of Bougainville: to establish forward airfields for strikes on Rabaul."^[11]

The area around Cape Torokina was settled on since, among other things, the Japanese were not there in force and had no airfield there. Also, Empress Augusta Bay had a somewhat protected anchorage, and the physical barriers in back of the cape (mountain ranges, jungle) meant that mounting a counterattack would be beyond the capabilities of the Japanese for weeks, possibly months.^[12]

Preparations for the landings

Bougainville lay within the Southwest Pacific Area, so operations were nominally under the command of General Douglas MacArthur, whose headquarters were in Brisbane, Australia. Although MacArthur had to approve all major moves, he willingly gave planning and operational control to Admiral William F. Halsey, Commander U.S. Third Fleet, headquartered at Nouméa on New Caledonia.^[13] In mid-October, Halsey set 1 November as the date for the invasion of Bougainville.^[14]

By early October, it was clear to the Japanese that a follow-up offensive to the Allied capture of the New Georgias was in the works, even though the target was uncertain. Commander of the Japanese Combined Fleet Admiral Mineichi Koga, flying his flag aboard battleship Musashi at Truk Lagoon, ordered all of his carrier aircraft to Rabaul. These planes would combine with the land-based air force already there and pound Allied bases and supply routes, a plan the Japanese called Operation RO.^[14] In the event, this plan achieved very little besides further attrition to the Japanese air arm.

To confuse the Japanese as to the Allies' real target, two other invasions were carried out. The Treasury Islands, a little to the southwest of the Shortlands, were occupied 27 October by the 8th Brigade Group, 3rd New Zealand Division under the command of Brigadier R.A. Row and a temporary landing was effected on Choiseul, one of the major islands in the Solomons chain.^[15]

Unlike on Guadalcanal and the New Georgias, the Allies could get no help in planning the invasion of Bougainville from British Commonwealth coastwatchers or Australian Army detachments. The Japanese had driven them off the island long before plans for Operation Cherry Blossom began.^[16]

Forces allocated

Rear Admiral Theodore Stark "Ping" Wilkinson, Commander Third Fleet Amphibious Forces, was assigned by Halsey to direct the landings at Cape Torokina from aboard his flagship, the attack transport George Clymer.

The ships under Wilkinson's command would disembark the I Marine Amphibious Corps under the command of Major General Alexander A. Vandegrift, USMC, victor of the land campaign on Guadalcanal. Vandegrift's force, a total of 14,321 men, consisted of the following:

• 3rd Marine Division (reinforced), Maj. Gen. Allen H. Turnage
• 37th Infantry Division (Army), Maj. Gen. Robert S. Beightler
• Advance Naval Base Unit No. 7^[17]

Landings at Cape Torokina

First day: 1–2 November 1943

Three groups of transports converged in Empress Augusta Bay on the morning of 1 November. Unfortunately, the existing maps of the Bougainville coast were highly unreliable German Admiralty charts from about 1890. A few corrections had been made by reconnaissance flights and submarine scouting, but some longitudes were still wrong. "Near the end of the approach, when the navigating officer of a transport was asked by the captain for his ship's position, he replied, 'About three miles inland, sir!'"^[18]

To the forces, as they approached, Empress Augusta Bay presented a magnificent but somewhat terrifying spectacle. Behind the curved sweep of the shore line, a heavy, dark green jungle...swept up over foothills and crumpled ridges to the cordillera which was crowned by a smoking volcano, Mount Baranga, 8,650 feet above sea level...It was wilder and more majestic scenery than anyone had yet witnessed in the South Pacific...^[19]

From the difficult landings at Guadalcanal and the New Georgias, Admiral Wilkinson learned a significant lesson about the necessity of rapid unloading and getting his slow, vulnerable transports away from the landing area. To this end, he only loaded his transports half full and his cargo ships one-quarter full, and made sure that 30% of the troops on the beach assisted in unloading.^[20]

The Japanese, having never conceived that the Allies were capable of a move as bold as one to Empress Augusta Bay, were unable to mount an air assault on the invasion fleet. Admiral Wilkinson, grateful that his transports were able to land almost the entire troop contingent and a large amount of materiel unmolested by air attack, ordered them out of the area around sundown.^[21]

Japanese response

When word of the landings reached Rabaul, Vice Admiral Tomoshige Samejima, Commander Japanese Eighth Fleet, immediately embarked a thousand troops onto five destroyer-transports at Rabaul and sent them to Cape Torokina to effect a counterlanding. Escorting the transports was a force of two heavy cruisers, two light cruisers and six destroyers led by Vice Admiral Sentaro Omori. During the night voyage to Torokina, the Japanese ships were spotted by an American submarine and possibly by a search plane. Concerned that he had lost the element of surprise, Omori radioed Samejima to ask permission to send the slow-moving transports back to Rabaul, but to continue with the combat ships to attack the American transports that he assumed were still in Empress Augusta Bay. Samejima concurred, and Omori pressed ahead with his cruisers and destroyers.^[22]

At the same time, Rear Admiral A. Stanton "Tip" Merrill was steaming toward the Bay with four light cruisers and eight destroyers. The two forces met in the early morning hours of 2 November in the Battle of Empress Augusta Bay, in which the Japanese lost light cruiser Sendai and destroyer Hatsukaze.

Carrier raid on Rabaul

Admiral Koga, while unwilling to risk his precious aircraft carriers, did dispatch seven heavy cruisers to Rabaul, arriving 3 November. News of the cruisers' arrival in the area of operations greatly concerned Admiral Halsey: the Bougainville beachhead was still quite vulnerable and he had no heavy cruisers at all to oppose a bombardment. Taking a huge gamble, he ordered the only carrier force under his immediate command, Task Force 38 under Rear Admiral Frederick C. Sherman, to cripple or sink as much of the combat shipping in Simpson Harbor as possible. The resulting air strike, launched from Sherman's fleet carrier Saratoga and light carrier Princeton on 5 November, sank no ships but inflicted enough damage to convince Koga to withdraw the heavy cruisers. The beachhead at Cape Torokina was never shelled by a Japanese heavy cruiser.^[23]

This raid demonstrated the crucial importance of air dominance. Not only did air power alone remove the threat to Bougainville from large surface ships, but the raid was carried out using the carriers' full complement of fighters; combat air patrol for Sherman's task force was provided by the land-based Air Solomons command throughout the mission.^[24]

November 1943: Expanding the beachhead

Early November

Defense and expansion of the position at Cape Torokina involved protracted and often bitter jungle warfare, with many casualties resulting from malaria and other tropical diseases. Except for patrol skirmishes, all of the major combat to expand the beachhead occurred in the Marine sector.

From 6–19 November, the remaining regiment of the 3rd Marine Division and the 37th Infantry Division (Army) were landed and the beachhead gradually expanded.^[25] On their third attempt, the Japanese successfully landed four destroyer-loads of men just beyond the eastern limit of the American beachhead before dawn on 7 November (to the great embarrassment of the PT boat base on Puruata Island, the Japanese effected this landing completely undetected by the Americans).^[26] The Marines annihilated this force the next day in the Battle of Koromokina Lagoon.^[27]

While escorting one of the invasion echelons to the Torokina beachhead on 9 November, some of Admiral Merrill's sailors witnessed an extraordinary incident that highlighted some of the extreme cultural differences at play in the Pacific Theatre:

On their way north, the bluejackets topside in destroyer Spence were goggle-eyed at an exhibition of Japanese bushido. Ordered to investigate a life raft, they observed what appeared to be seven bodies in it. The seven bodies suddenly sat up and started talking. One of them, apparently the officer, broke out a 7.7-mm machine gun, which each man in succession placed in his mouth, while the officer fired a round which shot the back of the man's head off. After six had been bumped off, the officer stood up, addressed a short speech in Japanese to Spence's commanding officer on the bridge, and then shot himself.^[28]

Parts of two Marine raider battalions drove away Japanese who were blocking the Piva branch of the Numa Numa Trail in the 8–9 November Battle for Piva Trail. The Marines then selected sites in the area for two airstrips (the fighter strip at the beach was already being built). Also on 9 November, Major General Roy S. Geiger, USMC, took over command of the I Marine Amphibious Corps from General Vandegrift. Four days later, he assumed command of the entire Torokina beachhead area from Admiral Wilkinson. By this time, the Perimeter, as it was called, covered about 7,000 yards of beach front and had a circumference of about 16,000 yards.^[29]

The trails to new airstrip sites had to be cleared, and General Turnage assigned this task to the 21st Marine Regiment. A Japanese ambush in the area resulted in the 13–14 November Battle of the Coconut Grove, ending with the Marines in control of the point where the Numa Numa and East West Trails crossed.^[29] Among those killed was Lieutenant Stanley P. Wright, whose poem "A Marine to His Girl" appeared in Eleanor Roosevelt's column My Day in January 1944.^[30]

Late November

At Rabaul, General Imamura was still convinced that the Allies did not mean to stay long at Torokina—he was sure it was just a stepping stone. He thus had no interest in mounting a decisive counterattack on the Allied beachhead using the substantial number of troops he already had in the southern part of Bougainville. Instead, he reinforced the Buka Island area, just off the north coast of the larger island, believing it to be the Allies' real target. In other words, the Army insisted on repeating the error of Guadalcanal; the Navy could not convince Imamura of the Americans' real intentions.^[31]

The 18–25 November Battle of Piva Forks effectively wiped out an entire Japanese infantry regiment. Even so, the beachhead was still not an entirely safe place. The day after the end of the Piva Forks action, as the sixth echelon of the invasion force was unloading at the beachhead, Japanese artillery fired on the landing ships, inflicting casualties. The Marines silenced these guns the following day.^[32]

On Thanksgiving Day, as the Battle of Piva Forks was ending, the Battle of Cape St. George took place in the waters between Buka and New Ireland. Three destroyer transports full of troops, escorted by two destroyers, all under the command of Captain Kiyoto Kagawa, were on their way to reinforce Buka. Admiral Halsey directed five destroyers under Captain Arleigh A. "31-Knot" Burke to intercept. The encounter ended with the sinking of Onami, Makinami and Yugumo, as well as the death of Captain Kigawa. No hits were scored on Burke's vessels.^[33]

On 28–29 November, the ill-fated Koiari Raid was carried out. A Marine detachment that was supposed to block a Japanese flank attack faced being overrun and had to be rescued.^[34]

December 1943: Securing the Perimeter

Under extremely difficult conditions, the Naval Construction Battalions (CBs or Seabees) and a group of New Zealand engineers carried on work on the three airstrips. The fighter strip at the beach was the first to begin full-time operations (10 December). The Japanese Army command at Rabaul was certain that the Allies would be moving on from Torokina; Imamura ordered a build-up of the defenses at Buin, on the southern tip of Bougainville.^[35]

In November and December the Japanese emplaced field artillery on the high ground around the beachhead, concentrated in a group of hills along the Torokina River overlooking the eastern perimeter. They shelled the beachhead, targeting the airstrips and the supply dumps.^[36] The 3rd Marine Division extended its lines to include the hills in a series of operations that lasted from 9–27 December. One hill, "Hellzapoppin Ridge", was a natural fortress 300 feet (91 m) long, with sharp slopes and a narrow crest that overlooked much of the beachhead.^[37] The Japanese constructed extensive positions on the reverse slopes using natural and artificial camouflage. The 21st Marines attacked Hellzapoppin Ridge but were driven off on 12 December. Several air strikes missed the narrow ridge completely.^[38] Finally, co-ordinated air, artillery, and infantry attacks resulted in the capture of Hellzapoppin Ridge on 18 December.^[39] In the days that followed, the 21st Marines were also involved in fighting around Hill 600A, which was captured by 24 December 1943.^[40]

On 15 December, the I Marine Amphibious Corps and General Geiger were replaced by the Army's XIV Corps, led by Major General Oscar W. Griswold, the victor of the land campaign on New Georgia. On 28 December, the 3rd Marine Division, exhausted because most of the fighting had taken place in its sector, was replaced by the Army's Americal Division under Major General John R. Hodge. The 37th Division (Army), left behind at Torokina when the Marines pulled out, was then placed under Griswold's XIV Corps.^[41]

January–February 1944: Encircling Rabaul

The aerial reduction of Rabaul

Rabaul had already been raided multiple times from 12 October through 2 November by the heavy bombers of General George C. Kenney's Allied Air Forces Southwest Pacific Area. Significant damage was done to ground installations and the Japanese adapted by moving aircraft facilities underground.^[42]

Completion of the airstrips on Bougainville would allow the Allies to use smaller planes against Rabaul. Only such low-flying techniques as dive bombing and glide bombing could permit the pinpointing of anti-aircraft installations and vessels in the harbor. The fighter strip on the beach at Torokina began operations on 10 December, the inland bomber strip "Piva Uncle" followed on Christmas Day, and the inland fighter strip "Piva Yoke" on 22 January.^[43]

General Ralph J. Mitchell, USMC, took over the command of all land-based planes in the theater, called Air Command, Solomons (Airsols), on 20 November. Once the three airstrips in the Torokina Perimeter were fully functional, Mitchell moved Airsols headquarters there from Munda on New Georgia Island.^[43]

The first raids by Airsols aircraft had limited success. Japanese anti-aircraft fire, especially from ships, had improved greatly since Kenney's raids, and inflicted significant damage on the raiders. Gradually, however, the Americans developed new formations and tactics that brought about increasing attrition among the Japanese fighter arm. The Navy could no longer risk exposing its ships to the relentless air attacks, and by late January, Admiral Kusaka had banned all shipping except barges from Simpson Harbor, which removed any remaining naval threat to the Torokina beachhead.^[44]

By mid-February, when the Allies captured the Green Islands (see below), the base was incapable of sending air power to interfere. As of 8 March, while the Battle for the Perimeter was beginning on Bougainville (see below), Air Solomons stopped bothering with fighter escorts for its bombing missions to Rabaul.^[45]

It is significant that the splendid harbor which in October 1943 had held some 300,000 tons of enemy shipping, and had sheltered powerful task forces of the Japanese Navy, was reduced to a third-rate barge depot.^[46]

Capture of the Green Islands

The Joint Chiefs of Staff had determined that Rabaul was to be encircled, with invasions of the Admiralty Islands and Kavieng on the north tip of the island of New Ireland, to begin 1 April at the earliest. Admiral Halsey, anxious to maintain offensive momentum, was unwilling to leave his forces idle until then. To that end, and to provide yet another airfield close to Rabaul, Halsey ordered his amphibious forces to invade the Green Islands, a group of small coral atolls about 115 miles east of Rabaul. Reconnaissance missions determined that the native Melanesians there were so well-disposed toward the Europeans, and had been so alienated by the Japanese, that no preliminary bombing or shelling would be performed.^[47]

On February 15, Admiral Wilkinson landed a contingent of New Zealanders under Major General Harold E. Barrowclough, who, like Griswold, was a veteran of New Georgia. With experience learned in previous invasions and extremely detailed staff work, the landings went off with great efficiency. In addition, interference from Japanese planes was minimal: "That so numerous a fleet could set thousands of troops ashore with impunity only 115 miles from Rabaul proved what good work AirSols had already accomplished."^[48]

The Greens provided a site for a PT boat base, and during the night of 1 March, PT-319 actually entered Simpson Harbor, and went undetected by the Japanese. This would have been inconceivable just two months earlier. In addition, a detachment of Seabees constructed an airfield, putting the Japanese base at Kavieng in range of AirSols planes for the first time.^[49]

March 1944: Japanese counterattack

Preparations

General Hyakutake commanded about 40,000 men in his 17th Army, plus had at his disposal about 20,000 naval personnel in the Southern part under Vice Admiral Tomoshige Samejima. One of the units in Hyakutake's command, the 6th Infantry Division under Lieutenant General Masatane Kanda, was reputed to be the toughest in the army. Hyakutake did not become convinced until December 1943 of Allied intent to remain permanently at Torokina. The resulting delay in Japanese offensive action gave Griswold plenty of time to deploy his men in suitable defensive positions.^[50]

Hyakutake's attack on the Perimeter would employ the 12,000 men of the 6th Infantry plus 3,000 reserves. His faith in the ultimate victory was such that he planned on taking Griswold's surrender at the Torokina airstrip on 17 March. The Japanese dragged the greatest concentration of field artillery they had yet assembled onto the ridges overlooking the perimeter. Griswold knew that allowing the Japanese to hold these ridges was better than stretching his own lines thin by occupying them himself.^[51]

On the American side, Hodge's Americal Division and the Beightler's 37th Infantry Division manned the Perimeter, while the 3rd Marine Defense Battalion and 49th Coast Artillery Battalion (Army) protected the beachhead. Griswold had learned on New Georgia that waiting for the Japanese to attack was a much surer way to victory than undertaking his own offensive operations in a jungle.

The Battle of the Perimeter

As far as the press and the American public were concerned, the war had moved on from Bougainville. "The struggle for the Perimeter went almost unnoticed outside the Pacific."^[52]

Hyakutake opened his all-out effort to throw the Americans off Bougainville, which came to be known simply as The Counterattack, on 9 March, and his men succeeded in capturing Hill 700 and Cannon Hill; General Beightler's 37th Division recaptured these positions on the afternoon of 12 March. Griswold gave credit to the destroyers that provided bombardment of the Japanese positions, suppressing their attempts at reinforcement.^[53]

Hyakutake's second thrust was delayed until 12 March. The Japanese advanced through a deep ravine to approach the Piva Yoke fighter strip, and succeeded in penetrating the Perimeter at one point. General Beightler responded by sending combined tanks and infantry to drive them back. Also, Japanese artillery that had been bombarding all three American airstrips was silenced by AirSols bombers. This action ended on 13 March. Hyakutake attempted twice more to penetrate the perimeter, on 15 and 17 March, but was driven back both times. The Japanese mounted a final attack on the night of 23–24 March, which made some progress but was then thrown back. On 27 March, General Hodge's Americal Division drove the Japanese off of Hill 260, and the battle came to a close.^[54]

During the Battle of the Perimeter, Air Solomons continued plastering Rabaul completely reducing its offensive capability. "...AirSols delivered at least one strike on Rabaul every day that weather permitted. An average of 85 tons of bombs was dropped on the area daily from 20 February to 15 May – a total of 7,410 tons by almost 9,400 sorties.^[55]

Aftermath

The Japanese army, having taken heavy losses during these operations, withdrew the majority of its force into the deep interior and to the north and south ends of Bougainville.^[56]

On 5 April 1944, the Americal Division's 132nd Infantry Regiment, after establishing patrol sweeps along Empress Augusta Bay, successfully launched an attack to capture the Japanese-held village of Mavavia. Two days later, while continuing a sweep for enemy forces, the Regiment encountered prepared enemy defences, where they destroyed about 20 Japanese pillboxes using pole charges and bazookas. Later, the 132nd, together with elements of the Fiji Defence Force, was tasked with securing the heights west of Saua River. The regiment and its allies captured Hills 155, 165, 500, and 501 in fierce fighting that lasted until 18 April, when the last of the Japanese defenders were killed or driven off.^[57]

The Americans were reinforced by the 93rd Infantry Division,^[58] the first African American infantry unit to see action in World War II.^[59] The Japanese, isolated and cut off from outside assistance, primarily concentrated on survival, including the development of farms throughout the island.^[56]

Morale fell deplorably ... after the loss of the Battle of the Perimeter; Admiral Takeda, in his narrative, notes robberies, insubordination and even mutiny. Hundreds of soldiers deserted and wandered through the jungle, living on anything they could find, even on snakes, rats and crocodiles.^[60]

The normal rice ration of 750 grams of rice for each soldier was cut in April 1944 to 250 grams, and beginning in September there was no rice ration. A large portion of the available army and naval personnel had to be put to work growing food. Allied pilots took delight in dropping napalm on these garden plots whenever possible.^[61]

Australian intelligence officers, after studying records, estimated that 8,200 Japanese troops were killed in combat during the American phase of operations, and 16,600 more died of disease or malnutrition.^[62]

Australian phase: November 1944 – August 1945

Strategic decisions

The invasion of the Philippines was tentatively scheduled for January 1945; however, Admiral Halsey had given General MacArthur such glowing reports of naval success in the Central Pacific that MacArthur chose to move up the Philippines operation to October 1944. MacArthur would need all the ground troops he could get for the Leyte landings, so by mid-July MacArthur had decided to withdraw Griswold's XIV Corps from Bougainville for rest and refit; it would be replaced by the Australian II Corps.^[63]

Since the perimeter around the all-important airfields at Cape Torokina was secure, the American high command had achieved its sole objective for the Bougainville campaign; all that was needed now, they believed, was to patrol the perimeter and man outlying strongpoints.^[61] The Australian military leadership had very different ideas about their role than the Americans did. Deeply frustrated and offended by having been squeezed out of strategic decision making by General MacArthur and others of the American command structure, General Sir Thomas Blamey, commander of the Australian Army, chose to take a much more aggressive approach on the ground. He determined that his forces would seek out and attack the enemy, even though capturing more territory and killing more Japanese on Bougainville could hardly affect the outcome of the war.^[64]

Handover

Lieut. General Sir Stanley Savige's Australian II Corps was a force of just over 30,000 men. It consisted of the Australian 3rd Division (7th, 15th and 29th Brigades) under the command of Major General William Bridgeford, as well as the 11th Brigade and the 23rd Brigade.^[63]

On 6 October, the first elements of the headquarters detachment of the 3rd Division landed. By mid-November, the 7th Brigade had relieved the U.S. 129th and 145th Regiments. On 22 November, Savige formally took command of Allied operations on Bougainville from Griswold. By 12 December, the replacement of frontline American troops by Australians was complete, and with the exception of a few service troops, all American service personnel had departed by 1 February 1945.^[65] The 3rd Division and 11th Brigade, reinforced by the Fiji Infantry Regiment, were posted to Bougainville. The 23rd Brigade garrisoned neighbouring islands.^[66]

The Australians now had full control of the perimeter, and General Savige could continue the operations against the Japanese without any fears of American criticisms. Those criticisms would come later, when the Australian parliament began to question the wisdom of Blamey's strategy.^[67]

Australian offensive operations

The Australians determined that Japanese forces on Bougainville, now numbering approximately 40,000, still had approximately 20 percent of their personnel in forward positions and that although understrength, were organized in combat-capable formations, including the 38th Independent Mixed Brigade and General Kanda's tough 6th Division.^[62] Savige issued his instructions on 23 December. Offensive operations would consist of three separate drives:^[68]

• In the north, the 11th Brigade would force the Japanese into the narrow Bonis Peninsula and destroy them.
• In the centre, the enemy was to be driven off Pearl Ridge, a feature from which both coasts of the 30-mile-wide island could be seen. From there, aggressive patrols could be launched to disrupt Japanese communications along the east coast.
• The main Australian drive would take place in the south where the bulk of the Japanese forces (Kanda's 6th Division) was located. It was to this goal that Savige assigned Bridgeford's 3rd Division.

Central front

The Battle of Pearl Ridge (30–31 December) revealed how far Japanese morale and stamina had fallen. The ridge was taken by a single battalion of Australians, suffering few casualties in the process. It was afterwards discovered that the position had been held by fully 500 defenders rather than the 80–90 that had originally been estimated.^[69] Activity in the central sector was from that point on confined to patrols along the Numa Numa Trail.^[70]

Northern front

Pursuant to General Savige's 31 December order to begin operations in the northwestern sector at the first opportunity, General J.R. Stevensons's 11th Brigade advanced along the coast, reaching the village of Rukussia by mid-January 1945.^[69] However, since the coastal plain was dominated by Tsimba Ridge, the Genga River could not be crossed in force until the Japanese had been dislodged from the crest of that ridge. In the resulting Battle of Tsimba Ridge, the Australians encountered determined resistance in heavily fortified positions, and it was not until 9 February that the last Japanese dug in on the western edge of the ridge were rooted out.^[71]

During the remainder of February and March the Australians drove the Japanese north past Soraken Plantation. Eventually, the approximately 1,800 Japanese fell back to a strong defensive line across the neck of the Bonis Peninsula. Because the 11th Brigade was exhausted from three weeks of jungle combat, frontal assaults were ruled out and an attempt was made to outflank the Japanese positions with an amphibious landing on 8 June. However, the landing force found itself pinned down and on the verge of being exterminated. Although Japanese losses were probably higher in the resulting Battle of Porton Plantation, the defenders received a boost in morale and the Australian command called off offensive operations in this sector for the time being.^[72] It was instead decided to contain the Japanese along the Ratsua front^[73] while resources were diverted to the southern sector for the drive towards Buin.^[74]

Southern front

On 28 December, General Savige issued orders to the 29th Brigade to begin the drive toward the principal Japanese concentration around Buin. After a month's fighting, the Australians were in control of an area extending twelve miles south of the Perimeter and six miles inland.^[75] Employing barges to outflank the Japanese, they entered the village of Mosigetta by 11 February 1945 and Barara by 20 February. The Australians then cleared an area near Mawaraka for an airstrip.^[76]

By 5 March, the Japanese had been driven off a small knoll overlooking the Buin Road; the Australians named this promontory after Private C.R. Slater who had been wounded during the fighting. During the 28 March – 6 April Battle of Slater's Knoll, determined Japanese attacks against this position were repulsed with heavy losses. "General Kanda's offensive was a disaster ... Indeed, the entire series of attacks by the Japanese is as inexplicable as the Australians' desire to conquer all the island." Having learned a costly lesson about the ineffectiveness of banzai charges, Kanda pulled his men back to a defensive perimeter around Buin and reinforced them with the garrisons from the Shortlands and the Fauros. The concentration was not complete until July.^[77]

Savige took two weeks to allow his forces to recuperate and resupply before restarting the drive on Buin. After repelling more futile Japanese attacks in the 17 April – 22 May Battle of the Hongorai River, his men crossed the Hari and Mobai Rivers. However, shortly after reaching the Mivo River their advance came to a halt as torrential rain and flooding washed away many of the bridges and roads upon which the Australian line of communications was dependent. This rendered large scale infantry operations impossible for almost a month and it was not until late July and into early August that the Australians were able to resume patrolling across the Mivo River.^[78] Before Savige could mount a substantial assault, news arrived of the dropping of the atomic bombs, after which the Australian forces mainly only conducted limited patrolling actions.^[79]

Conclusion

Combat operations on Bougainville ended with the surrender of Japanese forces on Bougainville on 21 August 1945. The Empire surrendered in Tokyo Bay on 2 September 1945. The last phase of the campaign saw 516 Australians killed and another 1,572 wounded. 8,500 Japanese were killed at the same time,^[80] while disease and malnutrition killed another 9,800 and some 23,500 troops and labourers surrendered at the end of the war.^[62] Historian Harry Gailey had this to say about the casualties suffered during the second phase of the Bougainville Campaign:

It was a terrible toll for an island whose possession after March 1944 was of no consequence in bringing the war to a close ... That the Australian soldiers performed so well when they had to know that what they were doing was in the larger sphere unnecessary and unappreciated at home says much for the courage and the discipline of the ordinary Australian infantryman.^[81]

Three Victoria Crosses were awarded during the campaign, one to a Fijian and two to Australians. Corporal Sefanaia Sukanaivalu of Fiji received the award posthumously for his bravery at Mawaraka on 23 June 1944.^[82] Corporal Reg Rattey received the award for his actions during the fighting around Slater's Knoll on 22 March 1945, while Private Frank Partridge earned his in one of the final actions of the campaign on 24 July 1945 during fighting along the Ratsua front.^[83][84] Partridge was the only member of the Militia to receive the VC which was the last of the war to an Australian.^[85]

Namesake

The U.S. Navy escort carrier USS Bougainville (CVE-100), in commission from 1944 to 1946, was named for the Bougainville campaign.^[86]

Notes

Footnotes

Citations

References

Further reading

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