 By the mid-1950s, early warning, fighter control, and ground controlled intercept (GCI) were performed by the Marine Air Control Squadrons as part of Marine Aviation.There were three MACS assigned to each Marine Amphibious Force.These squadrons provided air defense command and control centers known as Counter Air Operations Centers (CAOC) that relied on Marines to manually plot aircraft tracks on a large map based on voice or telephone calls from radar operators.