The 265th Air Defense Artillery Regiment is an air defense artillery regiment in the Florida Army National Guard. The unit was formed 19 October 1923 in the Florida National Guard as the 1st Separate Battalion, Coast Artillery Corps. It was reorganized and redesignated as the 265th Coast Artillery Regiment (CA) (Harbor Defense) (HD) in 1929. The 265th was activated for World War II and served in the harbor defenses of Galveston, Texas, Los Angeles, California, Key West, Florida, Sandy Hook, New Jersey, and Alaska until broken up into battalions in July 1944. The unit lineage was carried by two antiaircraft battalions organized in 1946, one of which was federalized in Florida during the Korean War. Consolidated with other units in 1959 as the 265th Artillery; reorganized in 1987 as the 265t