For the Allies, the landings were successful. The primary objective of securing a beachhead to establish an airfield were achieved in the weeks following the landing. Several secondary objectives were also achieved, including the 3rd Marine Division receiving its first engagement in the war, and the incremental reduction of Japanese air power around Rabaul. Throughout November, the balance of power at sea also began to shift in favor of the Allies, after the actions around Empress Augusta Bay and
Cape St. George, as they began to successfully combine improved tactics, technology and resources. Losses during the landings amounted to 78 killed in action and 104 wounded for the assaulting US troops. Against this, most of the 270 Japanese troops opposing the beachhead were killed. During the first three days of the landing, 192 bodies were located. In the days following the landings, the Japanese carrier aircraft were eventually able to reinforce the 11th Air Fleet, and several attacks were carried out on 5, 8, 11 and 17 November. These achieved some successes against reinforcement convoys but suffered sustained losses to anti-aircraft fire and defending Allied fighter aircraft. This ultimately degraded future Japanese naval air operations, depriving them of precious air assets to respond to Allied operations around
Makin and
Tarawa. Following the landings, the Japanese dispatched a sizeable naval force from
Truk, reinforcing the surface elements already at Rabaul in preparation for another attack on the Allied landing forces at Bougainville. Although several tankers and transports were interdicted by Allied aircraft on 4 November, the bulk of these reinforcements arrived safely at Rabaul. This included at least seven heavy cruisers, a light cruiser and several destroyers. These posed a significant threat to the lodgment around Cape Torokina. They arrived at a time when the US Navy's
capital ships were unavailable to respond, having been called back to
Pearl Harbor to prepare for the
Gilbert and Marshall Islands campaign. As a result, it was decided to neutralize the threat from the air. Throughout November, Allied land-based and carrier-based aircraft launched a series of
bombing raids against Rabaul. The main blow fell on 5 November, when aircraft from
Saratoga and
Princeton heavily damaged four heavy cruisers. The damaged cruisers had to withdraw to Truk. This ended the threat posed to the Allied forces around Cape Torokina by the Japanese surface fleet. Throughout November, as part of several subsequent echelons, the remainder of the 3rd Marine Division, the US
37th Infantry Division (under Major General
Robert S. Beightler) and Advance Naval Base Unit No. 7, landed at Cape Torokina. They arrived aboard
high-speed transports (APDs) and the slower LSTs, which had been held back initially due to fears of air attack. On 13 November, Major General
Roy Geiger assumed command of Allied forces on Bougainville from Wilkinson. As late as 25 November, the beachhead was still under hostile fire. As the sixth echelon of the invasion force was unloading, Japanese artillery fired on the landing ships, inflicting casualties. The Marines silenced these guns the following day. On 15 December responsibility for Bougainville passed from I Marine Amphibious Corps to the Army's
XIV Corps.
Base development Throughout November, US forces established a perimeter around Cape Torokina, during which significant base development work was undertaken with eight naval construction battalions (
Seabees) and a brigade of New Zealand engineers being deployed. This work included the construction of three airfields and an advanced
PT boat base on Puruata Island. Advance parties of the 25th, 53rd, 71st and 75th Naval Construction Battalions arrived on 1 November. The construction of
Torokina Airfield, a fighter airstrip, was assigned to the 71st Naval Construction Battalion. Work began on 3 November. Owing to the limited size of the beachhead, the choice of sites was limited, and the area was still under sniper fire. The swampy nature of the terrain required significant drainage work before construction could begin. The airstrip was completed on 10 December, allowing 18
Vought F4U Corsairs to land, although a
Douglas SBD Dauntless had already made an emergency landing on 24 November. Intended to handle 35 fighters or light bombers, Torokina eventually accommodated several times that number. dive bombers of VC-40 sortie from
Piva Airfield for a strike on Rabaul on 6 April 1944. The runway is surfaced with
Marston Mat. Construction of the larger
Piva Airfield for bombers was commenced on 29 November by the 36th Naval Construction Battalion, which had arrived three days before. The was carved out of dense jungle. The first aircraft landed on 19 December, and the airbase became operational on 30 December with the arrival of 10 Army transport aircraft. The runway was found to be too short and had to be extended by another . Construction of 35
hardstands, 7
hangars, and 26 other buildings was undertaken by the 71st Naval Construction Battalion. The 77th Naval Construction Battalion built a 5,000-man camp for the
Marine Aircraft Group 24, and the 36th added another 2,000-man camp. The 77th Battalion arrived on Bougainville on 10 December and began constructing a fighter airfield parallel to the bomber field. This was completed on 3 January, and the first aircraft landed on 9 January. Several weeks later, the 77th Battalion was instructed to extend the strip by . The two airfields were connected by taxiways and shared fuel tank farms and other facilities. The fuel tank farm consisted of a tank and 18 tanks, fed from a tanker mooring by a submarine pipeline and of overland pipe. The 75th Naval Construction Battalion had the task of repairing breaks in the pipeline caused by Japanese shellfire. Construction of a PT-boat base on Puruata Island was undertaken by the 75th Naval Construction Battalion, with help from the 71st and 77th Naval Construction Battalions. A wooden pile pier was built, along with
crash boat and fueling piers, and 18 small-boat moorings. Base facilities included sleeping quarters, mess halls, five steel-framed warehouses and an emergency hospital. The main medical facility was on Bougainville, built by the 36th Naval Construction Battalion. It consisted of 70
Quonset huts and a mess hall, with accommodation for 500 patients.
Expanding the beachhead Meanwhile, several engagements were fought on the periphery throughout the remainder of 1943 as the beachhead was secured. In the first of these, the
Battle of Koromokina Lagoon, a Japanese counterlanding by elements of the 17th Division, was repelled. An overland thrust by 6th Division elements from southern Bougainville was defeated at the
Battle for Piva Trail shortly afterwards. US forces slowly expanded their perimeter, systematically advancing to several inland defense lines throughout mid- to late-November. At the end of November, they launched an unsuccessful
raid on Koiari, to the south of the beachhead. Beginning on 15 December, the Japanese began an effort to move ground troops from southern Bougainville to the Torokina perimeter by barge. The effort amounted to little gain, with many of the barges losing their way or being intercepted by PT boats. Those troops that did manage to get ashore were attacked by Marine patrols. The last group of troops, having landed on the Magine Islands in Empress Augusta Bay, was destroyed with artillery on 20 December. Japanese nighttime bombing operations began on 15 December and continued for 10 days. Japanese artillery continued firing into the beachhead until they were
forced off Hellzapoppin Ridge in mid-December. The
Americal Division started arriving in December to relieve the Marines. On 15 December responsibility for command of the Torokina perimeter was assumed by Major General
Oscar Griswold's XIV Corps, inheriting a perimeter long and deep. Believing that the landing at Torokina was a ruse and would be followed by a further landing around Buka, Imamura reinforced the northern part of Bougainville instead of launching a concerted counterattack with the 15,000 (or more) troops that were stationed in southern Bougainville. By the time it became apparent that this assessment was wrong, the conditions required for a successful counterattack had passed and Hyakutake was ordered to delay his plans. In March 1944, the Japanese launched a
counterattack on the US perimeter around Cape Torokina, which was defeated with heavy casualties to their forces. A lull in the fighting on Bougainville followed until the later part of 1944, when Australian forces took over responsibility for the lodgment at Cape Torokina. Throughout 1944 and into 1945, the Australians worked to secure control of the island from the Japanese. They launched a series of drives to clear the northern, central and southern sectors. Ultimately, these were only partially completed by the time the war came to an end in August 1945. The Australians had advanced to the Bonis Peninsula in the north and had reached a position just short of Buin in the south. ==Notes==