The I Marine Amphibious Corps, or I MAC, was a formation of the

United States Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through combi ...

. It was created on 1 October 1942, with most of the staff transferred from Amphibious Corps, Pacific Fleet (ACPF). It was then deployed to the

South Pacific Area The South Pacific Area (SOPAC) was a multinational U.S.-led military command active during World War II. It was a part of the U.S. Pacific Ocean Areas under Admiral Chester Nimitz. The delineation and establishment of the Pacific Ocean Areas was ...

a U.S.-led multinational military command active during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

that was a part of the U.S.

Pacific Ocean Areas Pacific Ocean Areas was a major Allied military command in the Pacific Ocean theater of World War II. It was one of four major Allied commands during the Pacific War, and one of three United States commands in the Asiatic-Pacific Theater. Admir ...

first to

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

, then to New Caledonia.

History

When the Marine Corps was not satisfied with the leadership of its commander,

Major General Major general (abbreviated MG, maj. gen. and similar) is a military rank used in many countries. It is derived from the older rank of sergeant major general. The disappearance of the "sergeant" in the title explains the apparent confusion of ...

Clayton B. Vogel,

Commandant Commandant ( or ) is a title often given to the officer in charge of a military (or other uniformed service) training establishment or academy. This usage is common in English-speaking nations. In some countries it may be a military or police ran ...

Thomas Holcomb ordered

Alexander Vandegrift General Alexander Archer Vandegrift, USMC (March 13, 1887 – May 8, 1973) was a United States Marine Corps four-star general. During World War II, he commanded the 1st Marine Division to victory in its first ground offensive of the war, the B ...

to take command. Vandegrift, the commander of the

1st Marine Division The 1st Marine Division (1st MARDIV) is a Marine division of the United States Marine Corps headquartered at Marine Corps Base Camp Pendleton, California. It is the ground combat element of the I Marine Expeditionary Force (I MEF). It is th ...

during the

Battle of Guadalcanal The Guadalcanal campaign, also known as the Battle of Guadalcanal and codenamed Operation Watchtower by American forces, was a military campaign fought between 7 August 1942 and 9 February 1943 on and around the island of Guadalcanal in the ...

was promoted to

lieutenant general Lieutenant general (Lt Gen, LTG and similar) is a three-star military rank (NATO code OF-8) used in many countries. The rank traces its origins to the Middle Ages, where the title of lieutenant general was held by the second-in-command on the ...

. General Vandegrift carried on in command of the Corps when its next-designated commander for the invasion of Bougainville, Major General Charles D. Barrett, died following a fall from the balcony of his quarters in New Caledonia. General Vandegrift led I MAC during the invasion and was later made the Commandant. The Corps consisted of the

3rd Marine Division The 3rd Marine Division is a division of the United States Marine Corps based at Camp Courtney, Marine Corps Base Camp Smedley D. Butler in Okinawa, Japan. It is one of three active duty infantry divisions in the Marine Corps and together with th ...

, the

37th Infantry Division (United States) The 37th Infantry Division was a unit of the United States Army in World War I and World War II. It was a National Guard division from Ohio, nicknamed the "Buckeye Division". Today, its lineage is continued through the 37th Infantry Brigade Comb ...

, the

8th Brigade (New Zealand) The 8th Brigade was a formation of the New Zealand Military Forces, which served during the Second World War as part of the 2nd New Zealand Expeditionary Force. Eventually forming part of the 3rd Division, the brigade served in the Pacific Ocea ...

and the 53rd Naval Construction Battalion (

Seabee , colors = , mascot = Bumblebee , battles = Guadalcanal, Bougainville, Cape Gloucester, Los Negros, Guam, Peleliu, Tarawa, Kwajalein, Saipan, Tinian, Iwo Jima, Philippin ...

s). It conducted the invasion of Bougainville. When the 53rd was assigned to the Marine Corps it was redesignated "Naval Construction Battalion First Marine Amphibious Corps" On 15 April 1944, I MAC was renamed the III Amphibious Corps.''U.S. Marine Corps World War II Order of BattleGround and Air Units in the Pacific War, 1939–1945'',Gordon L. Rottman (2001). Westport, Connecticut: Greenwood Press. p. 108. .

Command structure

Commanding generals

*Major General Clayton B. Vogel: 1 October 1942 – July 1943 *Major General

: July 1943 – 27 September 1943 *Major General Charles D. Barrett: 27 September 1943 – 8 October 1943 *Major General Alexander Vandegrift: 8 October 1943 – 1 November 1943 *Major General

Roy S. Geiger General Roy Stanley Geiger (January 25, 1885 – January 23, 1947) was a United States Marine Corps four-star general who served in World War I and World War II. In World War II, he became the first Marine Corps general to lead a field army. Geig ...

: 9 November 1943 – 30 June 1945 (as III Amphibious Corps) *Major General Keller E. Rockey: 30 June 1945 – 10 June 1946

Chiefs of Staff

*Brigadier general Archie F. Howard: 1 October 1942 – July 1943 *Colonel Gerald C. Thomas: July 1943 – 9 November 1943 *Brigadier general

Alfred H. Noble General Alfred Houston Noble (October 26, 1894 – September 27, 1983) was a United States Marine Corps general who served in combat with the Marines from World War I in the Battle of Belleau Wood to World War II in the Pacific theater. His ...

: 10 November 1943 – 17 December 1943 *Brigadier general Oscar R. Cauldwell: 18 December 1943 – January 1944 *Brigadier general

Merwin H. Silverthorn Merwin Hancock Silverthorn (September 22, 1896 – August 14, 1985) was a highly decorated officer of the United States Marine Corps with the rank of lieutenant general. He was an expert in amphibious warfare and taught courses at Marine Corps t ...

: January 1944–30 June 1945 *Brigadier general William A. Worton: 30 June 1945 – 10 June 1946

Corps Artillery commanders

*Brigadier general

Pedro del Valle Pedro Augusto del Valle (August 28, 1893 – April 28, 1978) was a United States Marine Corps officer who became the first Hispanic to reach the rank of lieutenant general. His military career included service in World War I, Haiti and Nicaragua ...

: April 1944 – October 1944 *Brigadier general David R. Nimmer

Personnel Officer (C-1)

*Lieutenant Colonel

Joseph C. Burger Joseph Charles Burger (May 11, 1902 – February 1, 1982) was a decorated United States Marine Corps officer and college athlete. He rose to the rank of Lieutenant general (United States), lieutenant general and concluded his career as comman ...

: October 1942 – November 1943 *Colonel William J. Scheyer: November 1943 – September 1944 *Colonel Gale T. Cummings

Intelligence Officer (C-2)

*Lieutenant Colonel William F. Coleman *Lieutenant Colonel Sidney S. Wade

Operations Officer (C-3)

*Lieutenant Colonel Merrill B. Twining *Lieutenant Colonel

Edward W. Snedeker Edward Walter Snedeker (February 19, 1903 – May 5, 1995) was a highly decorated officer of the United States Marine Corps with the rank of lieutenant general. He was decorated with the Navy Cross, the United States military's second-highest dec ...

: September 1943 – December 1943 *Colonel Walter A. Wachtler: December 1943 – July 1945

Logistics Officer (C-4)

*Colonel Leonard E. Rea *Lieutenant Colonel Frederick L. Wieseman: August 1943 – August 1944 *Colonel Francis B. Loomis Jr.: August 1944 – July 1945 *Colonel

Earl S. Piper Earl Sanford Piper (February 14, 1905 – July 7, 1979) was a highly decorated officer in the United States Marine Corps with the rank of brigadier general. A veteran of the Nicaraguan Campaign, Piper distinguished himself under fire and receive ...

: July 1945 – July 1946

Plans Officer (C-5)

*Colonel Dudley S. Brown: October 1942 – July 1943 *Colonel Elmer H. Salzman *Colonel Benjamin W. Gally: July 1945 – 24 June 1946

Insignia

The Corps' insignia was a shield with a blue field emblazoned by the

Southern cross Crux () is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name ''Crux'' is Latin for ...

constellation in white and a square red diamond outlined with a white border, center. Various elements of the Corps used this basic design with their task insignia in white on the red center. * plain red diamond – Corps Headquarters *

Anti-aircraft cannon Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...

– Defense battalion * Balloon – Barrage Balloon Battalion * Crossed cannons –

Artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during siege ...

* Parachute – Paratroops * Skull – Raider battalions * Star – Supply and Service * Winged Engineer Castle – Aviation Engineers * The 1st Marine Division adopted the basic design with the number One emblazoned with the word Guadalcanal. * 23 – Later the 23rd Marines adopted the basic design without white outlining the diamond.

Notes

{{USMCmajorcommands 1942 establishments in the United States Corps of the United States Marine Corps Military units and formations established in 1942 Military units and formations of the United States Marine Corps in World War II