The History of ground based air defense in the United States Marine Corps dates back to the early 1930s with the establishment of the Advanced Base Force. World War II would be the high-water mark for air defense units when 20+ defense/anti-aircraft battalions were formed with many seeing significant action throughout the Pacific Theater. Following the war, the Marine Corps divested itself of most of its air defense capability at a time when the service was facing deep personnel cuts and fighting for its institutional survival. Beginning in the early 1950s the Marine Corps aligned itself with the Navy and their development of surface-to-air missiles (SAMs). The Marine Corps retained both flak weapons and SAMs throughout the 1950s until the fielding of the MIM-23 Hawk Missile System in 1960