The designation of both the 2nd and 3rd Raiders, who were refitting and training on New Caledonia, were changed 12 Sept.,1943. They would now be the 2nd and 3rd Battalions, 2nd Marine Raider Regiment (provisional 1MAC).
On 4 October the 2nd Raiders embarked on the President Hayes and disembarked 11 October at Guadalcanal. The 3rd Raiders embarked 6 October on the President Adams and disembarked at Kokumbona, Guadalcanal 11 Oct,1943 and encamped next to the 9th Marines, 3rd Marine Division.
The 2nd Raider Regiment was commanded by Col. Alan Shapley and Lt. Col. Joseph P. McCaffery assumed command of the 2nd Raiders. Lt. Col. Fred D. Beans was now in command of the 3rd Battalion.
Following the usual period of training and landing rehearsals, both Raider Battalions sailed 30 October, with the 1MAC task force for the assault on Bougainville scheduled for 1 Nov.1943. The operational plans for the landing were intricate with many assignments and missions. The dispositions of the Raider Battalions were as follows:
The 2nd Raiders were attached to 3rd Marine Division and Green Beach #1 at 0730 on the mainland.
The 3rd Raiders: I and K companies and part of Hq. Co. landed at 0730 on Green Beach #1 on the north side of Puruata Island and experienced heavy resistance. M company landed on Green Beach #2 on the mainland and their mission was to establish a roadblock on the Mission Trail a mile north of the Beachead. L company landed over Green Beach later in the day.
As the campaign progressed the Raiders were frequently attached to units of the 3rd Division and used as regular infantry battalions not as specialized units. However the Raiders played a key role in accomplishing the objectives of 1MAC and reaching the Final Beachhead Line. For 72 days the Raiders proved their worth and participated in the following major engagements:
- Battle of Piva Forks-9 Nov.1943
- Battle of Coconut Grove-13 Nov.1943
- Battle of Numa Numa Trail-19 Nov.1943
The two Raider Battalions performed brilliantly under the most difficult conditions and suffered very heavy casualties. On 12 Jan.1944, the Raiders were withdrawn from the combat zone and embarked on naval transport. On 14 Jan.1944, both Raider Battalions disembarked at Tassafaronga, unaware that the Marine Raiders were passing into history.