The Landings at Cape Torokina (1–3 November 1943), also known as Operation Cherryblossom, took place at the beginning of the Bougainville campaign in World War II. The amphibious landings were carried out by elements of the United States Marine Corps in November 1943 on Bougainville Island in the South Pacific, as part of Allied efforts to advance towards the main Japanese base around Rabaul under Operation Cartwheel. Coming in the wake of Allied successes at Guadalcanal and in the central Solomons, the landings were intended to secure a beachhead with the purpose of establishing several bases from which to project air and naval power closer towards Rabaul, in an effort to neutralize the large Japanese force that had been established there.
In the months leading up to the operation, Japanese airpower on Bougainville was degraded by Allied air strikes, while small parties of Allied reconnaissance forces landed around Bougainville and the surrounding islands to gather intelligence. On 1 November, a landing force based around the US 3rd Marine Division, reinforced with various supporting elements, landed at Empress Augusta Bay, on the western side of Bougainville. Situated well away from the main Japanese troop concentrations, the landing was met with only limited resistance on the ground. Japanese aircraft from Rabaul attempted to interdict the landing force, but their attacks proved ineffective and they were largely fought off by US and New Zealand fighters. By the end of the first day, a small perimeter had been established and the majority of the first wave of transports had unloaded their stores over the beachhead.
A strong Japanese naval force was dispatched in response from Rabaul in an effort to disrupt the landing operations and, overnight on 1/2 November, clashed with a force of US cruisers and destroyers during the Battle of Empress Augusta Bay. Heavy losses resulted for the Japanese and the force eventually returned to Rabaul. Meanwhile, on the second day, the remaining stores and equipment were unloaded from the transports. Over the course of the two days following the landing, the US troops ashore consolidated their beachhead and began patrolling operations as they worked to secure the perimeter. This was firmly established by 3 November, when Torokina Island was occupied.
In the aftermath, the US perimeter was slowly expanded and further echelons arrived to unload stores as base development operations began. By late November, an airstrip had been established inside the perimeter. This became fully operational in early December. Throughout the remainder of 1943, the perimeter was expanded further, allowing the establishment of several more airfields. These later played a key role in the neutralization of Rabaul from the air. Throughout 1944 and 1945, follow-on forces from the US Army and then the Australian Army arrived as the Allies conducted operations to secure the rest of the island. This was only partially completed by the time the war came to an end in August 1945.
Background
Geographically part of the Solomon Islands, but administratively part of the Territory of New Guinea at the time of the battle, Bougainville lies at the northwestern end of the Solomon Islands chain. Roughly shaped like a fiddle, the island is 125 miles (201 km) long and, at its widest point, 38 miles (61 km) across. It is dominated by thick jungle and large mountain peaks in its interior, with narrow beaches around the west coast. Situated south-east of New Britain, Bougainville offered the Allies another step in their advance through the Solomons towards the main Japanese base that had been established around Rabaul. The reduction and isolation of this base was a key Allied objective of the Operation Cartwheel. Seizure of Bougainville offered the Allies the ability to establish forward airfields from which to launch attacks against Rabaul, as well as anchorages around Empress Augusta Bay and Soraken, which could be utilized for Allied shipping.
The Japanese had invaded Bougainville in early 1942, and had established several airfields on the island, with key bases being constructed around Buka, at Kahili and Kieta, and on the Bonis Peninsula. From these bases, the Japanese had struck south towards Guadalcanal, in an effort to sever sea lanes of communication between the United States and Australia. Japanese air and naval movements around Bougainville had been monitored by a small group of Allied Coastwatchers, who were able to gain considerable intelligence through the native population of the island. However, by early 1943, with the conclusion of the Guadalcanal Campaign in the Allies' favor, and a string of defeats in the central Solomons, the Japanese had sought to consolidate their hold on Bougainville. They had slowly cleared the Coastwatchers from Bougainville, with the remaining personnel being withdrawn by the US submarine USS Gato in March 1943.
Initially, Allied planners had intended to capture Choiseul Island, at the northern end of New Georgia Sound; the Shortland Islands, off the southern coast of Bougainville; and, the Japanese airbase at Kahili, at the southern end of Bougainville. The fierce Japanese defense of the airfields at Munda Point forced them to reconsider. Leading up to the battle for Vella Lavella, a strategic decision, ultimately successful, had been made to bypass a large concentration of Japanese troops on the island of Kolombangara, between Guadalcanal and Vella Lavella. This caused the Allies to consider and adopt an indirect approach towards Rabaul. It was decided to bypass the Shortland Islands and Kahili, and to seize a lodgment on Bougainville, with the view to establishing an airbase from which to project airpower towards Rabaul. Under this plan Choiseul would not be captured, but would instead be raided as part of a diversion to draw Japanese attention away from Bougainville. The operation to secure a beachhead on Bougainville was codenamed "Cherryblossom" by the Allies.
Intelligence gathered by Coastwatchers and landing parties had determined that there were few suitable landing beaches. The only viable options were located in Empress Augusta Bay, around Cape Torokina on the western coast of Bougainville. However, the area around Cape Torokina was less than ideal for airfield construction, as it was largely swamp and it would require significant development to make construction viable. The bay was also open to the sea and was considered a "poor anchorage". It would be exposed during the coming monsoon. The location though, did have the advantage of isolation from the main Japanese concentrations around Buka and Buin in the north and south of the island, which would help Allied troops avoid a protracted battle while still enabling the neutralization of the Japanese airfields. US planning staff predicted that it would take the Japanese three months to launch a counterattack on Torokina due to the terrain and the distance from their main troop concentrations. If they did, the Torokina area formed an excellent defensive position that could be held by the forces available. It was bordered by natural obstacles: the Laruna and Torokina Rivers, and the mountains.
Opposing forces
Japanese
The Japanese forces defending Bougainville were part of General Harukichi Hyakutake's 17th Army, with the main infantry forces being drawn from the experienced 6th Division, under Lieutenant General Masatane Kanda. This formation had previously fought in China, including the Battle of Nanking. It was supported by the 4th South Seas Garrison Unit. In addition, elements of the 17th Division were scheduled to reinforce northern Bougainville in mid-November, and ultimately they played no part in repelling the landings at Cape Torokina on 1–3 November. The forces on Bougainville reported to the Eighth Area Army, under General Hitoshi Imamura, at Rabaul.
According to US Army historian John Miller, Allied intelligence estimated the strength of Japanese forces on Bougainville and the nearby islands were "37,500 soldiers and 20,000 sailors", while US Marine historians Henry Shaw, Douglas Kane and John Rentz, variously provide estimates of between 35,000 and 44,000 Japanese troops on Bougainville. The main concentrations of Japanese troops were estimated as follows: 17,000 in the southern part of the island; 5,000 around Buka, in northern Bougainville; 5,000 around Kieta on the eastern coast; 5,000 to 6,000 on the Shortland Islands; 3,000 in the vicinity of Ballale; and about 1,000 at Mosigetta, which was about 12 miles (19 km) inland from the southern end of Empress Augusta Bay. The 20,000 naval personnel were based in southern Bougainville where they formed part of Vice Admiral Tomoshige Samejima's 8th Fleet. These estimates were based on Ultra, augmented by documents captured in the Central Solomons, and by interrogation of prisoners of war. Post war, Japanese sources have indicated that Allied estimates of Japanese strength were close.
There were eighteen pillboxes concealed in the vicinity of the eventual landing area, but these were not fully manned. Troops in the immediate area of Cape Torokina numbered around 270 men, drawn mainly from a single company of the 1st Battalion, 23rd Infantry Regiment. They were supported by a single 75 mm field gun emplaced inside a log bunker, positioned in depth and surrounded smaller supporting bunkers and trenches. In addition, each bunker had two machine guns positioned to provide mutual support, and there were several mortars. The total strength included smaller positions on Torokina Island (held by a squad) and Puruata Island (held by a platoon). These troops had occupied Cape Torokina a few weeks prior to the landing.
There were six airfields on Bougainville located in the north, the south, and along the eastern coast. Allied air operations had heavily degraded Japanese air operations and air bases around Bougainville. Consequently, aircraft of the 11th Air Fleet were withdrawn from southern Bougainville to Rabaul in October. About 200 aircraft from the 11th Air Fleet were located around Rabaul at the time of the landings at Cape Torokina. A further 173 carrier aircraft were planned to arrive in late October, in preparation for a planned air offensive as part of Operation RO. This operation envisaged severing Allied lines of communication to inflict delay on the forces advancing towards Rabaul, while the Japanese reduced and consolidated their defensive perimeter in the Southwest and Central Pacific, in consequence of a decision made in September 1943. The carrier aircraft arrived at Rabaul over the course of 1 and 2 November, arriving too late to be employed by the Japanese around Cape Torokina in the first few days of the landing. On the first day only 120 aircraft of the 11th Air Fleet were used over the landing area. The attention of the carrier aircraft at Rabaul was largely diverted away from Empress Augusta Bay on 2 November, by heavy US air attacks on Rabaul, which continued into mid-November.
American
The Bougainville invasion was the ultimate responsibility of Admiral William F. Halsey, commander South Pacific Area, at his headquarters at Nouméa, New Caledonia. The landings were under the personal direction of Rear Admiral Theodore S. Wilkinson, commander III Amphibious Force, aboard his flagship, attack transport USS George Clymer. Also aboard was Lieutenant General Alexander A. Vandegrift, commander I Marine Amphibious Corps. Loaded aboard eight attack transports (APAs) and four attack cargo transports (AKAs), organized into three transport divisions, were the men of the 3rd Marine Division (reinforced), Major General Allen H. Turnage commanding. The fighting on Bougainville would be the division's first action of the war.
With Turnage aboard the USS Hunter Liggett was Commodore Lawrence F. Reifsnider, who had responsibility for the transports and attack cargo ships. The transport divisions were escorted by a screen consisting of 11 destroyers and were supported by various fleet tugs, minesweepers and minelayers. Anti-aircraft guns from the 3rd Marine Defense Battalion under Lieutenant Colonel Edward H. Forney and several field artillery batteries from the 12th Marine Regiment under Colonel John B. Wilson were assigned to the operation to provide support to ground troops once ashore.
Direct air cover for the landing was provided by Major General Nathan Twining's AirSols command, which included aircraft from the US Army Air Forces (USAAF), the United States Navy, the United States Marine Corps, and the Royal New Zealand Air Force (RNZAF). Lieutenant General George Kenney's Fifth Air Force was also tasked with supporting operations around Bougainville by conducting raids on Japanese air and naval assets around Rabaul.
US Ground Forces
I Marine Amphibious Corps (Lieutenant General Alexander A. Vandegrift)
3rd Marine Division (Major General Allen H. Turnage)
Prelude
Beginning in August 1943, Allied intelligence gathering activities began working to identify the disposition of Japanese troops as well as gathering key geographic and hydrographic information. Several parties of US and Australian personnel were landed around Bougainville and the surrounding areas throughout the months preceding the operation. These parties were inserted by a variety of means (motor boat, submarine, or seaplane) to carry out patrols, study the terrain, and gather intelligence from locals, while aerial reconnaissance was also undertaken to the north and south of Bougainville. Submarines were employed to survey coastal areas and collect hydrographic information.
In the month prior to the landings, Allied aircraft assigned to AirSols launched over 3,200 sorties against Japanese airfields surrounding the proposed landing site and the wider Bougainville area in an effort to reduce the ability of the Japanese to interfere with the landings from the air. On the day of the landing, a naval task force, Task Force 39 under Rear Admiral Aaron S. Merrill, including several cruisers and destroyers, bombarded the airfields around Buka and the Bonis Peninsula. Proceeding south, a fire mission on the Shortlands followed, as part of a diversionary plan to take Japanese attention away from Cape Torokina.
Elsewhere, the Treasury Islands were secured by New Zealand and US forces in the days prior to the landings at Cape Torokina, to secure anchorages around Blanche Harbor and establish a radar station to support air operations over Bougainville. A battalion of Paramarines also launched a raid on Choiseul to divert Japanese attention from Bougainville. In response, the Japanese sent thousands of reinforcements to Choiseul.