After winter training on Parris Island and Hilton Head Island, the battalion boarded USS Chaumont on 5 April 1940 at Charleston, South Carolina. They sailed for Pearl Harbor, Territory of Hawaii arriving on 7 May 1940. A number of Marine Corps defense battalions were sent to the Pacific during this time period in order to defend outlying American possessions as detailed in War Plan Orange. During their first 8 months in Hawaii the battalion supplied numerous reconnaissance and advance parties to begin the preliminary work of supplying and defending the installation on Midway Island. On 27 January 1941 the Chief of Naval Operations directed the 3rd Defense Battalion to move to Midway. They arrived at Midway on 14 February 1941 and remained garrisoned there 11 September when they were relieved by the 6th Defense Battalion. 3rd Defense Battalion returned to Hawaii on 15 September 1941 on board .
