The 4th Coast Artillery Group was redesignated from (probably HHB) 4th Coast Artillery Regiment on 1 November 1944 in the Panama Canal Zone, where redesignated as the Harbor Defenses of Balboa on 2 January 1945.
The 4th Coast Artillery Battalion was constituted 3 October 1944 and activated 1 November 1944; in August 1945 Battery C was located at Seymour Island, Galápagos.The 4th CA Battalion was inactivated (less Batteries A and D) on 1 February 1946