Naval Mobile Construction Battalion 40
A former United States Navy Seabee battalion specializing in expeditionary construction, combat-zone engineering, and disaster relief.
Last updated October 14, 2026
AI crawler reads
No AI crawler has read this profile since Oct 28, 2026.
Overview
Naval Mobile Construction Battalion 40, commonly known as NMCB 40 or the Fighting FORTY, was a United States Navy Seabee unit based at Port Hueneme, California. Its role was not the sale of commercial products but the delivery of expeditionary engineering and construction capability for naval and joint military operations. The battalion could deploy personnel, heavy equipment, design and planning expertise, and logistical support to austere or hostile locations, where it built and maintained airfields, roads, camps, ammunition facilities, communications infrastructure, utilities, and other operational facilities. The unit was commissioned on 6 November 1942 at Camp Allen, Virginia, during the expansion of the Seabees in World War II. Its first major deployment took it to Espiritu Santo, where it helped construct the Lion 1 airfield and associated support facilities. It later served on Los Negros Island with the United States Army's 1st Cavalry Division. During a Japanese attack, members of the battalion participated in the defense of the perimeter while continuing their engineering duties. This combat experience led to the enduring nickname Fighting FORTY. The battalion subsequently restored the Momote airfield, which became operational in May 1944, and received recognition associated with the Army unit citation awarded for its service on Los Negros. In 1945, it worked on Okinawa, repairing routes and facilities while operating amid enemy action and severe typhoons. The wartime construction battalion was decommissioned on 28 November 1945. NMCB 40 was reactivated in 1966 for service in Vietnam. It supported advance-base operations around Chu Lai by building ammunition magazines and maintaining supply routes, and it returned for additional tours at Chu Lai and Phu Bai. Several specialized Seabee teams also operated in South Vietnam. During the Cold War, the battalion became closely associated with the development of Diego Garcia. Beginning in March 1971, it constructed a communications station and airfield on the remote British atoll using an over-the-beach logistics concept. The communications facility became operational in March, while the runway was completed in July, establishing a major United States military presence in the Indian Ocean. NMCB 40 returned to Diego Garcia in 1980. The battalion's later history combined wartime contingency construction with humanitarian assistance and multinational exercises. During the response to Iraq's 1990 invasion of Kuwait, it moved from Guam to Saudi Arabia and built six camps and aviation-support facilities for Marine forces. It supported Operation Restore Hope in Somalia by repairing roads and constructing or assisting with schools, orphanages, sanitation facilities, and logistical sites. In Bosnia and Herzegovina, during Operation Joint Endeavor, it closed and dismantled camps, conducted convoy operations, and completed contingency projects supporting implementation of the Dayton Peace Agreement. After 2001, NMCB 40 supported operations connected with Afghanistan and Iraq, including the movement of millions of pounds of construction equipment from California to Kuwait and the deployment of an air detachment to Southwest Asia. Pacific deployments included construction and maintenance work in Japan, Okinawa, Guam, South Korea, Diego Garcia, and other locations. The battalion also assisted after the 2004 Southeast Asian tsunami, supported humanitarian construction in Panama, and participated in regional exercises such as Cobra Gold and New Horizons. In the United States, it conducted cleanup and recovery work after Hurricane Katrina in Louisiana and Mississippi. Its final major combat deployment included Afghanistan operations in 2010. A reinforced air detachment deployed to Kandahar, while the main body operated in northern and eastern Afghanistan. The unit contributed to the construction of Forward Operating Base Deh Dadi II, described in the source material as one of the largest United States military earthmoving efforts in a combat zone since World War II. NMCB 40 was decommissioned at Port Hueneme on 12 September 2012. Its legacy rests on the Seabee model of combining military readiness, construction expertise, self-sufficient field operations, and disaster-response capability.
History
NMCB 40 began as the 40th Construction Battalion, commissioned on 6 November 1942 at Camp Allen, Virginia. During World War II it deployed to the South Pacific, first working at Espiritu Santo on the Lion 1 airfield and related facilities. On Los Negros Island it was attached to the Army's 1st Cavalry Division and helped defend the perimeter during a Japanese attack. The battalion's conduct during that action produced the Fighting FORTY nickname and contributed to Army recognition for the unit's service. It subsequently restored Momote airfield, which became operational in May 1944, and later deployed to Okinawa, where it rebuilt major supply routes while facing enemy activity and typhoons. The battalion was decommissioned on 28 November 1945 during the postwar drawdown. The unit was reactivated in 1966 as MCB 40 for Vietnam service. It supported the 3rd Marine Amphibious Force at Chu Lai, constructing ammunition magazines and maintaining supply routes. It made further Vietnam deployments to Chu Lai and Phu Bai, while Seabee teams operated at several South Vietnamese locations. In 1968 the Navy redesignated construction battalions as Naval Mobile Construction Battalions, making the unit NMCB 40. In the 1970s the battalion combined Vietnam-era contingency work with Cold War infrastructure missions. Its most consequential project began on Diego Garcia in March 1971. Working with supplies brought over the beach, NMCB 40 built a communications station and airfield on the remote atoll. The communications station became operational in March and the runway in July, creating an important United States military facility in the Indian Ocean. The battalion returned to Diego Garcia in 1980. Following Iraq's invasion of Kuwait in 1990, NMCB 40 deployed from Guam to Saudi Arabia. It supported Marine forces by constructing six camps, placing more than 20,700 cubic meters of concrete, and preparing aviation parking, taxiways, fueling areas, and maintenance pads. In Somalia, it supported Operation Restore Hope with road cleanup, logistical facilities, sanitation work, and construction or repair of schools and orphanages. During Operation Joint Endeavor in 1996, the battalion shifted from a European deployment to Bosnia and Herzegovina, where it helped close fourteen camps, conducted tactical convoy operations, and completed projects supporting implementation of the Dayton Peace Agreement. The post-2001 period brought repeated deployments to Southwest Asia, the Pacific, and other theaters. In 2003 the unit supported operations related to Iraq and Afghanistan and moved large quantities of construction equipment to Kuwait. Its 2004-05 Pacific deployment included work in Japan, Okinawa, South Korea, Diego Garcia, and other locations, as well as tsunami-response engineering in Southeast Asia, humanitarian construction in Panama, and regional military exercises. It conducted recovery work after Hurricane Katrina in 2005. Later rotations included dispersed missions in Guam, the Pacific, Central Asia, Africa, Europe, the Caribbean, and South America, often combining construction with camp maintenance, readiness training, and multinational exercises. In 2010, a reinforced air detachment went to Kandahar while the main body deployed to northern and eastern Afghanistan. The battalion worked on Forward Operating Base Deh Dadi II and other sites during the coalition troop surge. NMCB 40 was decommissioned at Port Hueneme on 12 September 2012. Its history illustrates the Seabee approach of pairing combat readiness with practical construction, infrastructure restoration, and humanitarian assistance.
- 2012
Decommissioning
[1]The battalion was formally decommissioned at Port Hueneme on 12 September.
- 2010
Afghanistan deployment
[1]NMCB 40 deployed to multiple Afghan regions and contributed to the construction of Forward Operating Base Deh Dadi II.
- 2005
Tsunami and hurricane relief
[1]The battalion supported Southeast Asian tsunami recovery and later Hurricane Katrina relief in the United States.
- 1996
Operation Joint Endeavor
[1]The battalion supported IFOR operations in Bosnia and Herzegovina by closing camps and completing contingency projects.
- 1992
Operation Restore Hope
[1]NMCB 40 provided construction, road, sanitation, school, and logistical support in Somalia.
- 1990
Gulf contingency deployment
[1]The unit deployed from Guam to Saudi Arabia after Iraq invaded Kuwait and built major Marine-support infrastructure.
- 1971
Diego Garcia development
[1]NMCB 40 began construction of a communications station and airfield on Diego Garcia.
- 1968
Redesignation as NMCB 40
[1]The Navy changed the designation from MCB to NMCB, creating the Naval Mobile Construction Battalion 40 name.
- 1966
Vietnam reactivation
[1]MCB 40 was reactivated and deployed to Chu Lai in support of Marine advance-base operations.
- 1945
Okinawa operations and wartime decommissioning
[1]The battalion rebuilt Okinawan supply routes and was decommissioned on 28 November after World War II.
Products and positioning
A highly deployable United States Navy Seabee engineering unit designed to provide construction, infrastructure repair, and disaster-relief capability in contested or austere environments.
Military engineering service · 1942
Expeditionary construction
NMCB 40 deployed construction personnel and heavy equipment to contested or remote locations. Its work included roads, airfields, camps, ammunition magazines, communications facilities, utilities, maintenance areas, and other operational infrastructure required by naval, Marine, Army, and joint forces.
Emergency infrastructure service · 1942
Humanitarian and disaster-relief engineering
The battalion provided engineering assessments, debris removal, facility repair, sanitation support, school construction, and temporary structures after conflicts and natural disasters. Examples included tsunami relief in Southeast Asia, Hurricane Katrina recovery, work in Somalia, and humanitarian construction exercises in Panama and the Pacific.
Marketing campaigns
- 2005Hurricane Katrina relief
Louisiana · Mississippi · United States
The battalion conducted cleanup, relief, and construction operations after the hurricane devastated the Gulf Coast.
Outcome. Its work supported emergency response and accelerated recovery in the New Orleans and Gulfport areas.
- 1996Operation Joint Endeavor
Bosnia and Herzegovina
NMCB 40 supported IFOR by closing camps, operating tactical convoys, drilling for water, and completing force-support construction.
Outcome. Fourteen camps were closed or disestablished and nineteen critical projects were completed in support of the Dayton Peace Accord.
- 1992Operation Restore Hope
Somalia
The unit supported multinational forces and local communities with roads, schools, sanitation, orphanage work, and logistical facilities.
Outcome. Construction and repair activities supported humanitarian and security operations in southern and northern Somalia.
- 1990Gulf contingency construction
Saudi Arabia · Kuwait region
The battalion built Marine-support camps and aviation infrastructure after Iraq's invasion of Kuwait.
Outcome. Six camps and extensive aviation-support surfaces were completed during the contingency operation.
- 1971Diego Garcia development
Diego Garcia · Indian Ocean
NMCB 40 built a communications station and runway from an austere island base using over-the-beach logistics.
Outcome. The communications facility and runway entered service in 1971, forming the foundation of a long-term United States military installation.
- 1944Los Negros and Momote airfield operations
Los Negros Island · New Guinea region
The battalion defended its assigned perimeter with the 1st Cavalry Division and then restored the damaged Momote airfield.
Outcome. The airfield became operational on 18 May 1944, and the unit received Army recognition for its wartime service.
Brand decisions
2012
Formal decommissioningOtherBackground
After decades of wartime, contingency, and humanitarian deployments, the Navy ended the unit's active existence.
Action taken
NMCB 40 was decommissioned at Port Hueneme on 12 September 2012.
Aftermath
The Fighting FORTY ceased to operate as an active battalion.
1968
Adoption of the NMCB designationStrategyBackground
The Navy reorganized the naming convention for its construction battalions during the Vietnam era.
Action taken
MCB 40 became Naval Mobile Construction Battalion 40.
Aftermath
The new designation reflected the unit's mobile, deployable construction role and remained in use until decommissioning.
Recent events
- 2012
NMCB 40 decommissioned at Port Hueneme[1]
Other · Leadership change
Naval Mobile Construction Battalion 40 was formally decommissioned at Naval Construction Battalion Center Port Hueneme on 12 September 2012.
- 2010
NMCB 40 conducts Afghanistan construction deployment[1]
Other
The battalion deployed air and main-body elements to Afghanistan in support of coalition operations, including work at Forward Operating Base Deh Dadi II.
- 2005
NMCB 40 supports Hurricane Katrina recovery[1]
Other
The battalion performed humanitarian relief, debris-clearing, and construction work in the New Orleans and Gulfport areas after Hurricane Katrina.
Sources1 sources
Cite this profile: Cite the canonical profile. /brand-wiki/naval-mobile-construction-battalion-40 · Editorial policy · How profiles are compiled