In the immediate aftermath of the fall of New Georgia, the Allies seized other islands in the vicinity, to include Arundel, Vella Lavella, and Kolombangara. Thereafter the South Pacific command turned its attention to the next major step in the encirclement of Rabaul. There were several options, but the final choice was a landing on Bougainville, the largest island in the Solomons group. A month later MacArthur’s command would assault Cape Gloucester on the western end of New Britain. Rabaul would then be within range of Allied land-based fighter aircraft coming from two directions. Air power thus could neutralize the Japanese bastion and allow it to be by-passed. The scheduled D-day for Bougainville was 1 November 1943.

Several factors dictated Halsey’s scheme of maneuver for the offensive. First, he had too few transports and Marines to make a direct assault on the heavily defended enemy airfields located on the northern and southern ends of the island. Another consideration was the range of land-based fighters from bases in the Central Solomons—they could only effectively cover a landing in the southern half of Bougainville. The planners settled on the Empress Augusta Bay-Cape Torokina region on the western side of the island. Defenses were negligible there, and Bougainville’s difficult terrain would prevent any rapid reaction from enemy ground forces located elsewhere on the island. Once ashore, the invasion force would seize a defensible perimeter, build an airfield, and eventually neutralize the remainder of the island from this enclave. A patrol landed by submarine in late September discovered that the areas back of the landing beaches were swampy. Aerial reconnaissance in October also discovered the construction of new defenses. Neither of these facts changed the plan, however.

For this operation, the 2d and 3d Raider Battalions were organized as the 2d Raider Regiment, with Shapley in command. Lieutenant Colonel Joseph P. McCaffery took over the 2d Raider Battalion. Because of insufficient shipping, the initial landing consisted of just two regiments of the 3d Marine Division, reinforced by the raiders and the 3d Defense Battalion. The remainder of the Marines and the Army’s 37th Division would follow at a later time.

On 1 November, the 3d and 9th Marines, assisted by the 2d Raider Battalion, seized a swath of the coast from Cape Torokina to the northwest. At the same time, the 3d Raider Battalion (less Company M) assaulted Puruata Island off Cape Torokina. Japanese defenses in the landing area consisted of a single company supported by a 75mm gun. One platoon occupied Puruata and a squad held Torokina Island, while the rest of the Japanese infantry and the gun were dug in on the cape itself.

The small Japanese force gave a good account of itself. The 75mm gun enfiladed the eastern landing beaches, while machine guns on the two small islands and the cape placed the approaches to this area in a crossfire. The result was havoc among the initial right flank assault waves, which landed in considerable disorder. The 75mm gun destroyed four landing craft and damaged 10 others before Sergeant Robert A. Owens of the 1st Battalion, 3d Marines silenced it. (He received a posthumous Medal of Honor for his single-handed charge against the key position.)

The 2d Raider Battalion, landing just to the left of Owens’ battalion, suffered from the gun, and from mortar and machine gun fire raking the beach. McCaffery succeeded in reorganizing his force on the beach and launching an attack that swept away the enemy defenses, but he fell mortally wounded in the process. Other battalions farther to the west met little or no resistance, except from high surf that caused many landing craft to broach. Company M, 3d Raiders, temporarily attached to the 2d Raider Battalion, moved out at noon and occupied a blocking position 1,500 yards up the Piva Trail, the main avenue of approach into the beachhead. The 3d Raiders silenced the machine guns on Puruata on D-day, and destroyed the last defenders on that island by late afternoon on 2 November. Total raider casualties to this point were three killed and 15 wounded.

Over the next several days the Marines advanced inland to extend their perimeter. There were occasional engagements with small enemy patrols, but the greatest resistance during this period came from the terrain, which consisted largely of swampland and dense jungle once one moved beyond the beach. The thing most Marines would remember about Bougainville would be the deep, sucking mud that seemed to cover everything not already underwater. On 4 November another unit relieved the 2d Raider Battalion on the line, and both battalions of the raider regiment were attached to the 9th Marines. The raiders maintained responsibility for the roadblock, and companies rotated out to the position every couple of days.

Two small attacks hit Company E at the roadblock the night of 5 November, and a larger one struck Company H there two days later. Company G came forward in support and the enemy withdrew, but the Japanese kept up a rain of mortar shells all that night. On the morning of 8 November Companies H and M occupied the post and received yet another assault, this one the heaviest yet. In midafternoon Companies E and F conducted a passage of lines, counterattacked the enemy, and withdrew after two hours.

The next morning Companies I and M held the roadblock as L and F conducted another counterattack preceded by a half-hour artillery preparation. Japanese resistance was stubborn and elements of Companies I and M, and the 9th Marines eventually moved forward to assist. Shortly after noon the enemy retired from the scene. Patrols soon discovered the abandoned bivouac site of the Japanese 23d Infantry Regiment just a few hundred yards up the trail. In the midst of this action PFC Henry Gurke of Company M covered an enemy grenade with his body to protect another Marine. He received a posthumous Medal of Honor for his heroic act of self-sacrifice.

The raider regiment celebrated the Marine Corps’ birthday on 10 November by moving off the front lines and into division reserve. Other than occasional patrols and short stints on the line, the next two weeks were relatively quiet for the raiders. The Army’s 37th Division began arriving at this time to reinforce the perimeter. On 23 November the 1st Parachute Battalion came ashore and temporarily joined the raiders, now acting as corps reserve. Two days later the 2d Raider Battalion participated in an attack extending the perimeter several hundred yards to the east, but it met little opposition.

On 29 November Company M of the 3d Raider Battalion reinforced the parachutists for a predawn amphibious landing at Koiari several miles southeast of the perimeter. This operation could have been a repeat of the successful Tasimboko Raid, since the Marine force unexpectedly came ashore on the edge of a large Japanese supply dump. However, the enemy reacted quickly and pinned the Marines to the beach with heavy fire. Landing craft attempting to extract the force were twice driven off. It was not until evening that artillery, air, and naval gunfire support sufficiently silenced opposition that the parachutists and raiders could get back out to sea.

Army troops continued to pour into the enlarging perimeter. On 15 December control of the landing force passed from the I Marine Amphibious Corps to the Army’s XIV Corps. The Americal Division gradually replaced the 3d Marine Division, which had borne the brunt of the fighting. For much of the month the 2d Raider Regiment served as corps reserve, but these highly trained assault troops spent most of their time on working parties at the airfield or carrying supplies to the front lines. On 21 December the raiders, reinforced by the 1st Parachute Battalion and a battalion of the 145th Infantry, assumed the position formerly occupied by the 3d Marines. The regiment remained there until 11 January, when an Army outfit relieved it. The raiders boarded transports the next day and sailed to Guadalcanal.