20th Marine Regiment was a Composite Engineer Regiment 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 c ...

that fought 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 World War II by country, vast majority of the world's countries—including all of the great power ...

.U.S. Marine Corps World War II Order of Battle Fleet Marine Force Ground Units, Rottman p. 220''

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Subordinate units

The regiment was a composite of three different types of battalions and a headquarters and service company: * Headquarters & Services Company * 1st Battalion, A, B,& C Companies 4th Engineer Battalion * 2nd Battalion, D, E, & F Companies 4th Pioneer Battalion * 3rd Battalion, G, H, & I Companies 121st Naval Construction BattalionUS Marine Corps World War II order of battle : ground and air units in the Pacific War, 1939-1945, date=2002, Gordon L. Rottmann, Greenwood Press, Westport, Connecticut, p. 218-22

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History

20th Marines was formed on June 15, 1943, at

Marine Corps Base Camp Lejeune Marine Corps Base Camp Lejeune () is a United States military training facility in Jacksonville, North Carolina. Its of beaches make the base a major area for amphibious assault training, and its location between two deep-water ports ( Wilmingt ...

North Carolina North Carolina () is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. The state is the List of U.S. states and territories by area, 28th largest and List of states and territories of the United ...

, it originally consisted of three battalions and was assigned to support the

4th Marine Division The 4th Marine Division is a reserve division in the United States Marine Corps. It was raised in 1943 for service during World War II, and subsequently fought in the Pacific against the Japanese. Deactivated after the war, the division was re- ...

. The 1st and 2nd Battalions were made up of the 4th Marine Engineers and Pioneers while the 3rd Battalion was formed with US Navy Construction Battalion personnel also known as

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

s. During the war the Regiment involved in the battle of Roi Namur,

Battle of Saipan The Battle of Saipan was a battle of the Pacific campaign of World War II, fought on the island of Saipan in the Mariana Islands from 15 June to 9 July 1944 as part of Operation Forager. It has been referred to as the "Pacific D-Day" with the ...

and

Battle of Tinian The Battle of Tinian was a battle of the Pacific campaign of World War II, fought on the island of Tinian in the Mariana Islands from 24 July until 1 August 1944. The 8,000-man Japanese garrison was eliminated, and the island joined Saipan ...

. On Saipan, the 4th Marine Division assigned 2/20 and 3/20 (4th Pioneers and 121st CB) as the shore party The regiment was inactivated on August 31, 1944 with the 4th Engineer and 4th Pioneer Battalions reassigned to the Division itself. While the 121st NCB remained at Tinian to work on the airfield, the 4th moved on preparing for Iwo Jima. 133 NCB was posted to the slot vacated by the 121st. With the 20th Regiment gone the 133rd was assigned to the 23rd Marines as their shore party and the 4th Pioneers were assigned to the 25th Marines as theirs. The 4th Engineers were then under divisional control. A note concerning the 121st. That Battalion had Marine Officers assigned to it. When the 19th CB was assigned to the Marine Corps 11/05/42 it lost one company and 1/4 of Hq Co.19th Naval Construction Battalion Historical Information, Seabee Museum website

/ref> Those men were assigned to the Fleet Marine Force Replacement Group, New River, NC (19th replacement group) which would form the core of the 121st CB when it was formed 05/03/43.121st Naval Construction Battalion Historical Information, Seabee Museum websit

/ref> On 7 July 43 the Battalion was redesignated as the Third Battalion Twentieth Marines. The Battalion was shore party for the 23rd Combat team on beaches blue 1 and 2 on Saipan. On Tinian there were two small beaches on the North end where an assault landing could be made. The rest of the island had coral cliffs up to 15 feet in height at the waters edge negating any assault plans. However, the Marine Corps asked the Seabees if they could come up with an idea to facilitate a landing in one of these other areas. Commodore Paul J. Halloran (CEC) CB theater commander provided drawings of a conceptual landing ramp for the 18th and 121st CBs to fabricate. They mounted steel beams salvaged from Saipans abandoned sugar mill on LVT-2s to create a portable assault ramps. If they worked they would allow the Marines to outflank Tinian's prepared defenses. The Marine General was skeptical and ordered that the ramps be put through a 100 vehicle use tests. The Seabee creation was named a Doodlebug. It worked exactly as the Marines had hoped.The Doodlebug, Naval History and Heritage Command, U.S. Navy Seabee Museum webpage, Port Hueneme, Ca

/ref> Regiment's Commanders *Lieutenant Colonel Nelson K. Brown (15 June 1943 - 22 August 1943) *Colonel Lucian W. Burnham (23 August 1943 - 9 April 1944) *Lieutenant Colonel Nelson K. Brown (10 April 1944 - 31 August 1944)

Unit awards

United States Navy Presidential Unit Citation ribbon

Presidential Unit Citation (US), Presidential Unit Citation with blue enamel star

References

{{DEFAULTSORT:Eng20 Regiments of the United States Marine Corps Inactive units of the United States Marine Corps Military units and formations established in 1943

Subordinate units

History

Unit awards

See also

Further reading

References