Order of Battle

 bigpigeon.us webpage WWII Japan > Order of Battle > OOB - South Pacific, © 2024 by Robert A. Christiansen, updated by RAC 14 Mar 2024. 
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This webpage provides an organizational context to the ground war fought against Japan by the US Marine Corps and US Army in the Solomon Islands in the South Pacific in 1942–43.

• The US Navy's Pacific Area Command in Pearl Harbor, Hawaii, led by Admiral Chester Nimitz, oversaw Allied military activities in the South Pacific Area.
• South Pacific Area commanders were Admiral Robert L. Ghormley (17 May–18 Oct 1942) and Admiral William Halsey Jr. (18 Oct 1942–15 Jun 1944), based at Noumea in the French Colony of New Caledonia. ​

Relevant webpages in Big Pigeon's WWII Japan module:

• The Solomons Naval War 
• The Solomon Islands, Guadalcanal (August 1942–February 1943)
• The Solomon Islands, New Georgia (June–August 1943)
• The Solomon Islands, Bougainville (November 1943–March 1944)

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               Order of Battle - Guadalcanal Campaign, 1942-43
               for webpage South & SW Pacific > Solomon Is., Guadalcanal
The landing, 7 August 1942:

• 1st Marine Division (Vandegrift): 1st Marine Regt., 5th Marine Regt., 11th Marine Regt. (artillery, elts.)
• 2nd Marine Division (DeCarre): 2nd Marine Regt. (+)

Subsequent reinforcements to 12 December 1942:

• 1st Marine Division: 7th Marine Regt., 18 September 1942–12 December 1942.
• Americal Division (Patch): 132nd Inf. Regt., 164th Inf. Regt., 182nd Inf. Regt., 13 October 1942–
• 2nd Marine Division: 8th Marine Regt., 2 November 1942–

• 147th Inf. Regt. (sep.), 12 November 1942–

Change in command, 12 December 1942:

• 1st Marine Division began leaving Guadalcanal & ground command passed from Vandegrift to Patch, US Army. On 2 January 1943, XIV Corps assumed command with Patch as corps commander.

Later reinforcements:

• 25th Infantry Division (Collins): 17 December 1942–
• 2nd Marine Division: 6th Marine Regt. (+), 4 January 1943–

Commentary on the Guadalcanal Campaign:

• The Americal Division is officially known as the 23rd Infantry Division.
• The 25th Infantry Division completed landing on Guadalcanal 4 January 1943.
• Advance bases for the Guadalcanal Campaign were in New Georgia, to the southeast of Guadalcanal.
• The Guadalcanal Campaign ended on 8 February 1943 after the withdrawal of Japanese forces from Guadalcanal.

               New Georgia Islands Campaign, 1943.
XIV Corps (Griswold): (Initial phases of the campaign were under 43rd Division control.)
New Georgia:

• 43rd Infantry Division (Hester, Wing): 30 June 1943–
• 37th Infantry Division (Beightler): 7 Jul 1943–
• 25th Infantry Division (Collins): 22 July 1942–

Commentary on the New Georgia Campaign:

• The primary goal of the New Georgia Campaign was to seize the Japanese airbase at Munda.
• The New Georgia Campaign included multiple amphibious landings, including landings on Rendova Is. and Villa Lavella Is.
• Not included here are the one or more battalion-sized Marine Corps units that participated. 

               Bougainville Island Campaign, 1943-44.
I Marine Amphibious Corps (Vandegrift, Geiger): 1 November 1943–15 December 1943
XIV Corps (Griswold): 15 December 1943–
The landing:

• 3rd Marine Division (Turnage): 1 November 1943–28 December 1943
• 37th Infantry Division (Beightler): 6 November 1943–

Subsequent reinforcements:

• Americal Division (Hodge): December 1943–
• 93rd Infantry Division (colored) (Lehman, elts.): March 1944–

Commentary on the Bougainville Campaign:

• The Bougainville landing was preceded by a landing on the Treasury Is.
• US forces occupied only a small portion of Bougainville.
• In March 1944, Japanese forces launched a major counterattack which had some initial success.