On 9 March 1971 the first units of NMCB 40 were deployed to the small British atoll island of Diego Garcia in the middle of the Indian Ocean.

Their mission was to construct a high priority communications station and airfield "from scratch" in the same manner as the Seabees did in the island hopping days of World War II.

in northern Somalia "Fighting FORTY" aided the Somalis through the construction and repair of schools and orphanages and many other basic life support needs.

NMCB FORTY planned and operated with the Army's 1st Armored Division Implementation Force (IFOR) to close and disestablish fourteen base camps ahead of schedule.

FORTY completed camp deconstructions and provided contingency construction support for nineteen critical force projects—enabling enforcement of the Dayton Peace Accord.

In August 2003, the battalion's Air Detachment redeployed from Okinawa directly to Southwest Asia to support ongoing global war on terrorism operations in Kuwait, Iraq, and Afghanistan.

The battalion completed numerous construction projects at the main body site in Okinawa and other locations throughout Japan, including Atsugi, Fuji, Iwakuni, and Sasebo.

Within a month of deployment, a group of 50 Seabees responded to the devastating tsunami that struck Southeast Asia, conducting critical engineering assessments on government facilities and airfields.

They also supervised the construction of tension fabric structures and supported runway working parties that delivered relief supplies to the people of Indonesia.

Finally, the battalion deployed Seabees in support of a Joint Task Force exercise, New Horizons 2005, to provide humanitarian construction and engineering operations for the nation of Panama.

In September 2005, "Fighting FORTY" conducted humanitarian relief, clearing, and construction operations for the citizens of greater New Orleans, Louisiana and Gulfport, Mississippi following the devastation brought on by Hurricane Katrina.

In the end, the battalion completed over 42,000 man-days of safe, high quality construction throughout the Pacific and Central Command Theaters of Operation, resulting in a combined cost savings of over $14.8M.

There were complexities of the battalion's deployment, with sites located throughout Kuwait; the Horn of Africa; Andros Island; Guantanamo Bay, Cuba; Rota, Spain, Romania, Sao Tome; and Ghana.

NMCB 40 participated in eight annual PACOM exercises: Cobra Gold, Freedom Banner, Balikatan, Voluntary Demonstration of Response (VDR), Cooperation Afloat Readiness and Training (CARAT), Foal Eagle/Key Resolve, Talisman Saber, and Ulchi Focus Guardian.

The exercises included Humanitarian and Civic Assistance (HCA) projects which continue to further the U.S. strategic goal of Theater Security Cooperation in key regions around the world.

NMCB 40 also opened up the newest 26-person detail site in Timor-Leste (formerly known as East Timor) and constructed, repaired and renovated over eight schools for the Timorese Government.

This operation was critical to shape and enable the Government of the Islamic Republic of Afghanistan (GIRoA) to protect the Afghan people and provide a secure environment for sustainable peace.