Following the Japanese invasion of Guadalcanal, Admiral Ernest King, Commander in Chief, United States Fleet and Chief of Naval Operations during World War II, drew up a joint basic plan for the occupation and defence of Efate in March 1942. Its terms stipulated that the US Army was to defend Efate and support the defence of ships and positions. Under the plan, the US Navy was assigned four key roles:
- Construct, administer and operate a naval advance base, seaplane base, and harbor facilities;
- Support Army forces in the defence of the island;
- Construct an airfield and at least two outlying dispersal fields;
- Provide facilities for the operation of seaplane-bombers.
On April 8 1942, approximately 500 men from the 4th Defense Battalion, 45th Marines arrived on Efate from New Caledonia. Elements of the 1st Naval Construction Battalion (the Seabees) arrived on May 4 1942 and were critical to the establishment of operations on Vanuatu. They were quickly reinforced by a ground echelon of VMF-212 and 4 Marine Defense Battalion, and later by 24 Regiment.