page_title: Naval Mobile Construction Battalion 133
section_title: WWII – Iwo Jima: 133 Naval Construction Battalion
hierarchical_section_title: Naval Mobile Construction Battalion 133 / History / WWII – Iwo Jima: 133 Naval Construction Battalion
caption_attribution_description: English: LSM 206 landing A Co 133 NCB D8's at 0935
context_page_description: 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 World War II 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.
context_section_description: The unit's history began on 17 September 1943 at Camp Peary, Virginia, where it was commissioned as the 133rd Naval Construction Battalion (NCB).  After 7 months of training at Davisville, Gulfport and Port Hueneme the battalion's first overseas assignment was NAS Honolulu, Territory of Hawaii (May–October 1944).  On 15 October 1944 word was received that the battalion  was going to be attached to the 4th Marine Division. On 30 October the assignment came for Operation Detachment at Iwo Jima.  D-day was planned for 19 February 1945. When 133 was attached to the 4th it was filling a billet that had been vacated when the 121st CB was released by the Marine Corps.  The 121st CB had been transferred to the Marine Corps and re-designated as the 3rd Battalion of the 20th Marine Regiment.  After the assault of Tinian the 20th Marines were inactivated.  Then both the 1st battalion (4th Engineers) and 2nd battalion (4th Pioneers)  were placed under Divisional control.  Third battalion 3/20 or the 121st, was returned to the Navy creating the vacancy 133 was posted to.  Before joining the 4th at Camp Maui, the 133rd was put through the Army's Pacific Jungle Combat Training Center (CTC) at Schofield Barracks on Oahu, TH.  Camp Maui was located along the North shore at Haiku-Pauwela. 
  Once assigned to the division the battalion had each company detached and "tasked" to a different element of the 23rd Marines for shore party training. The battalion's shore party assignment was to provide the beach support required by the forward lines of the 23rd, 24th, and 25th Marines . The division shipped out for Island "X" on 31 December with V Amphibious Corps (VAC) as T.U. 56.2.2 of Baker Landing Group.  Baker group was commanded by Major General C.B Cates USMC of the 4th Marine Division.  When they were a few days out the men learned they were heading to a place they had never heard of called Iwo Jima. The assault for Iwo was based upon Tinian where the 2nd and 4th Marine Divisions assault had been "reinforced" by Marine Engineering Regiments with the 18th and 121st CBs as 3rd battalions respectively.  On D+3 the Jap airfield was secured and the Seabees had it operational in a few hours.(the Iwo Jima landing map is notated that the Marine Corps planned to have control of Iwo Jima in 3 days also) For Iwo the 4th and 5th Marine Divisions were "reinforced" by the 133rd and 31st NCBs. Marine Corps landing maps indicate that for O-1 (objective Day 1) Motoyama Airfield No. 1 would be secured and 133 was tasked to get it operational. However, D+5 the assignment was given to the 31st CB due to the losses 133 had suffered.  The next day 62 CB  landed with the 3rd Marine Division and was designated the lead Battalion for Airfield No. 1.  The 31st was assigned Airfield No. 2 and the 133rd was given Airfield No. 3. In just seven days the heavy equipment of the 3 combined battalions had Airfield No. 1 operational.
  The 133rd CB and the 4th Marine Pioneer Battalion were the primary units of the "Assault" shore parties for the 23rd and 25th Regimental Combat Teams (RCT) on the 4th Marine Division's yellow and blue beaches. The 4th Marine Division's single Pioneer Battalion was assigned to the 25th RCT.  USMC tactical operations required  another Pioneer battalion for the 23rd RCT's Assault. The 121st CB had been tasked as such at Roi-Namur, Siapan, and Tinian so giving that task to the 133rd was simply standard 4th Marine Division operations. Tasking Seabees for USMC shore party at Iwo was a fortuitous decision for the Corps.  The CBs brought organic elements the Marines did not have, specifically, bulldozers with winches and D8s 132–148 Hp compared to the Marine Corp's TD 18s 72–80 Hp.  Afterwards, the after action reports recommended all USMC bulldozers be equipped with winches as they had none.  The history is, that "on the beach at Iwo, bulldozers proved to be worth their weights in Gold" and the CBs had the biggest and the best the Navy could provide. 
  The Landing Force Shore Party Commander was OIC of the 8th Marine Field Depot.
  Hq Co was posted to the 
caption: LSM 206 loaded with A Co 133's Shore Party equipment & 3 D8s at approx. 0935 were landed on the wrong beach Red Beach 2
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