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.

Naval Advance Base Espiritu Santo or Naval Base Espiritu Santo, most often just called Espiritu Santo, was a major advance Naval base that the U.S. Navy Seabees built during World War II to support the Allied effort in the Pacific. The base was located on the island of Espiritu Santo in the New Hebrides, now Vanuatu, in the South Pacific. The base also supported the U.S. Army and Army Air Corps, U.S. Coast Guard, and US Marine Corps. It was the first large advance base built in the Pacific. By the end of the war it had become the second-largest base in the theater. To keep ships tactically available there was a demand for bases that could repair and resupply the fleet at advance locations, rather than return them to the United States. Prior to December 7th, Pearl Harbor was the U.S. fleet's largest advance base in the Pacific. Espiritu became capable of all aspects necessary to support the Fleet's operations from fleet logistics in fuel, food, and ammunition, to transport embarkation for combat operations or returning to the continental United States. The ship repair facilities and drydocks were capable of attending to most damage and routine maintenance. Had it not existed, ships would have had to return to Pearl Harbor, Brisbane, or Sydney for major repairs and resupply. The base became a major R and R destination for the fleet.