This was the US reinforcement of the marine forces in American Samoa (January 1942).
The first step in this process was the despatch of Brigadier General Henry L. Larsen’s 2nd Marine Brigade (Reinforced), based on the 8th Marines, and this became first element of the 2nd Marine Division to be forwarded into the Pacific theatre. The 2nd Marine Brigade disembarked at Pago Pago on 19 January 1942, just one week after a Japanese submarine had shelled this US possession. No damage had been inflicted and the only casualty had been a US Navy officer, who suffered only minor wounds.
The first elements of Marine Aircraft Group 13 arrived on 11 March to provide air support. A US Navy patrol aeroplane detachment was attached to the group, and this was the first occasion in which a US Navy aviation unit had been subordinated to a US Marine unit. The ships which had transported the brigade returned to the USA bearing the original naval station’s and the defence battalion’s dependents. The 2nd Marine Brigade’s plan to defend Tutuila island scattered its units in small detachments around this third smallest of the islands, and thereby opened the possibility that they might have been defeated in detail had the Japanese not cancelled their ‘Fs’ plan to invade New Caledonia, the Fijian islands group and the Samoan islands group in July 1942: Major General Kyutake Kawaguchi’s ‘Kawaguchi’ Detachment with the 41st Regiment and 124th Regiment had been assigned to this task.
Doctrine called for early-warning outposts to be established around a large island and the bulk of the defence force to be positioned in a central location to protect critical installations such as the port and airfield, and allow it to counterattack in force. On 29 April, the 2nd Marine Brigade and MAG-13 were placed under the command of the Defense Force, Samoan Group, a division-equivalent command under Major General Charles F. B. Price. This command also controlled US Marine units in western Samoa. Between August 1942 and September 1943 the Defense Force supported the occupation of the Ellice islands group some 600 miles (965 km) to the north-west.
The first ‘Seabee’ construction force arrived on Tutuila in July 1942 to relieve the contractors who had previously worked on the defence installations, but the Seabee unit was sent on to Espíritu Santo. Some contractors volunteered to remain and continue to work on projects augmented by local labour until another Seabee unit arrived in August.
The 8th Marines left for Guadalcanal in October 1942 and were replaced by the 3rd Marines. The 2nd Marine Brigade was disbanded in March 1943, but the 3rd Marines remained on Tutuila until May. Seven US Marine replacement battalions, raised on the US east coast, were trained and acclimatised between December 1942 and July 1943 at the Replacement Training Center, Tutuila. The Defense Force, Samoa Group, was disbanded in December 1943.