| 20th Marine Regiment | |
|---|---|
| Active | June 15, 1943 — August 31, 1944 |
| Country |  United States of America |
| Branch |  United States Marine Corps |
| Type | Engineer regiment |
| Engagements | World War II |
20th Marine Regiment was a Composite Engineer Regiment of the United States Marine Corps that fought during World War II. [1]
The regiment was a composite of three different types of battalions [2] and a headquarters and service company:
20th Marines was formed on June 15, 1943, [1] at Marine Corps Base Camp Lejeune, North Carolina, it originally consisted of three battalions and was assigned to support the 4th Marine Division. 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 Seabees. [4] During the war the Regiment involved in the battle of Roi Namur, Battle of Saipan and Battle of Tinian. On Saipan, the 4th Marine Division assigned 2/20 and 3/20 (4th Pioneers and 121st CB) as the shore party [5] 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. [6]
When the 19th CB was assigned to the Marine Corps 11/05/42 it lost one company and 1/4 of Hq Co. [7] 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. [8] 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. [8]
On Tinian there were two small beaches on the North end where an assault landing could be made. [9] 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. [9] 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. [9] It worked exactly as the Marines had hoped. [9]
Regiment's Commanders
United States Naval Construction Battalions, better known as the Navy Seabees, form the U.S. Naval Construction Force (NCF). The Seabee nickname is a heterograph of the initial letters "CB" from the words "Construction Battalion". Depending upon context, "Seabee" can refer to all enlisted personnel in the USN's occupational field 7 (OF-7), all personnel in the Naval Construction Force (NCF), or Construction Battalion. Seabees serve both in and outside the NCF. During World War II they were plank-holders of both the Naval Combat Demolition Units and the Underwater Demolition Teams (UDTs). The men in the NCF considered these units to be "Seabee". In addition, Seabees served as elements of Cubs, Lions, Acorns and the United States Marine Corps. They also provided the manpower for the top secret CWS Flame Tank Group. Today the Seabees have many special task assignments starting with Camp David and the Naval Support Unit at the Department of State. Seabees serve under both Commanders of the Naval Surface Forces Atlantic/Pacific fleets as well as on many base Public Works and USN diving commands.
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 and Guam as a base for the Twentieth Air Force.
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 the 1st Marine Aircraft Wing (1stMAW) and the 3rd Marine Logistics Group forms the III Marine Expeditionary Force. The division was first formed during World War II and saw four years of continuous combat in the Vietnam War. Today, elements of the 3rd Marine Division are continuously forward deployed and forward postured to carry out the US Government's mission of a Free and Open Indo-Pacific in conjunction with its sister services.
The 2nd Marine Division is a division of the United States Marine Corps, which forms the ground combat element of the II Marine Expeditionary Force. The division is based at Marine Corps Base Camp Lejeune, North Carolina and headquartered at Julian C. Smith Hall.
The 23rd Marine Regiment is a reserve infantry regiment of the United States Marine Corps. It is headquartered in San Bruno, California and falls under the command of the 4th Marine Division and the Marine Forces Reserve.
On 15 June 1944, United States Marine forces landed on the southwest coast of the island of Saipan in the central Marianas chain; these were followed a day later by US Army forces. This invasion was part of Operation Forager, an effort to recapture the entire Marianas chain from the Empire of Japan.
1st Battalion, 23rd Marines (1/23) is one of 32 infantry battalions in the United States Marine Corps, and one of only eight battalions found in the reserve. It is located throughout Texas and Louisiana consisting of approximately 1000 Marines and Sailors. They fall under the command of the 23rd Marine Regiment and the 4th Marine Division.
2nd Battalion, 23rd Marines (2/23) is a reserve infantry battalion in the United States Marine Corps located throughout the Western United States consisting of approximately 1000 Marines and Sailors. They fall under the command of the 23rd Marine Regiment and the 4th Marine Division.
The Civil Engineer Corps (CEC) is a staff corps of the United States Navy. CEC officers are professional engineers and architects, acquisitions specialists, and Seabee Combat Warfare Officers who qualify within Seabee units. They are responsible for executing and managing the planning, design, acquisition, construction, operation, and maintenance of the Navy's shore facilities. The Civil Engineer Corps is under the command of the Chief of Civil Engineers and Commander, Naval Facilities Engineering Systems Command. On 12 August 2022, RADM Dean VanderLey relieved RADM John W. Korka, becoming the 46th commander of NAVFAC and Chief of Civil Engineers.
When World War II broke out the United States Naval Construction Battalions (Seabees) did not exist. The logistics of a two theater war were daunting to conceive. Rear Admiral Moreell completely understood the issues. What needed to be done was build staging bases to take the war to the enemy, across both oceans, and create the construction force to do the work. Naval Construction Battalions were first conceived at Bureau of Yards and Docks (BuDocks) in the 1930s. The onset of hostilities clarified to Radm. Moreell the need for developing advance bases to project American power. The solution: tap the vast pool of skilled labor in the U.S. Put it in uniform to build anything, anywhere under any conditions and get the Marine Corps to train it. The first volunteers came skilled. To obtain these tradesmen, military age was waived to age 50. It was later found that several past 60 had managed to get in. Men were given advanced rank/pay based upon experience making the Seabees the highest paid group in the U.S. military. The first 60 battalions had an average age of 37.
The V Amphibious Corps (VAC) was a formation of the United States Marine Corps which was composed of the 3rd, 4th and 5th Marine Divisions in World War II. The three divisions were the amphibious landing force for the United States Fifth Fleet with two goals, removal of Japanese forces from islands so U.S. Seabees could build advance bases to project US power. In doing this VAC was notably involved in the battles for Tarawa, Saipan, and Iwo Jima. V Amphibious Corps was commanded by General Holland 'Howlin Mad' Smith followed by General Harry Schmidt.
The 22nd Marine Regiment is an inactive United States Marine Corps infantry regiment. The regiment was commissioned in 1942 and was placed under the command of the 1st Provisional Marine Brigade in 1944, and the 6th Marine Division in 1945. It took part in fighting at the battles of Eniwetok, Guam, and Okinawa. The regiment also participated in the occupation of northern China following the war. 22d Marines was decommissioned in March 1946.
The 19th Marine Regiment was a composite engineer regiment of the United States Marine Corps subordinate to the 3rd Marine Division. It existed from September 1942 until September 1944. In December 1943 there was a large change of command in the Regiment. Marine engineer regiments were eventually disbanded in favor of independent engineering battalions within the parent Marine divisions.
The 18th Marine Regiment was a composite engineer regiment of the United States Marine Corps subordinate to the 2nd Marine Division. It was disbanded during the war, with the 1st and 2nd battalions remaining in the Division.
The 17th Marine Regiment was a composite engineer regiment of the United States Marine Corps subordinate to the 1st Marine Division. It was formed primarily from units of the Division, and was inactivated during war with the 1st and 2nd battalions remaining in the Division.
Amphibious Construction Battalion TWO is an amphibious construction battalion in the United States Navy based in Little Creek, Virginia. Amphibious Construction Battalion ONE is its sister unit based in Coronado, California.
Naval Mobile Construction Battalion 133 is a United States Navy Construction Battalion, otherwise known as a Seabee Battalion, homeported at the Naval Construction Battalion Center. The unit was formed during WWII as the 133rd Naval Construction Battalion. It saw action and was decommissioned shortly after the war ended. The unit was reactivated as Mobile Construction Battalion 133 for the Vietnam War and remains an active unit today.
Naval Mobile Construction Battalion 25 or NMCB 25 is a Navy Reserve Seabee unit that is headquartered at Port Hueneme, CA. Its World War II predecessor was one of three CBs transferred to the Marine Corps in the late summer of 1942 as combat engineers. Those three battalions were attached to composite Marine Engineer Regiments as the third battalion of their respective regiment. All of them remained with the Marine Corps for the next two years before they were released and returned to the Navy. At the end of World War II the battalion was decommissioned. In 1961, it was recommissioned in the Naval Construction Force Reserve where it remains today.
Naval Construction Battalion 5 was commissioned on May 25, 1942 at Camp Allen Va. The battalion went to Port Hueneme and shipped out for the first of two deployments in the Pacific. When the war ended CB 5 was decommissioned in the Philippines. On July 10, 1951 the Battalion was re-commissioned as a MCB and remains an active unit today.
When WWII broke the United States had no mechanized flamethrowing capability. It is believed that an officer in the 754th U.S. Army tank battalion came up with the idea of mounting a flame thrower on a M3 Light tank on the island of New Caledonia. The Army used the idea on New Georgia and the Marines during the Battle of Bougainville. After which further development passed to the U.S. Army. Chemical Warfare Service at Schofield Barracks, Territory of Hawaii. There the Army reached out to the United States Naval Construction Force for assistance. The Seabees accepted the offer and converted or modified nearly 400 tanks for the Army. Those weapons set the standard for the U.S. through the Korean War. It was not until 1955 that a superior flame throwing tank replaced the Shermans the Seabees created.
