The 863rd Bombardment Squadron is a former United States Army Air Forces unit. It was first organized as the 518th Bombardment Squadron in October 1942, when it replaced a National Guard unit participating in antisubmarine patrols off the Atlantic coast, becoming the 13th Antisubmarine Squadron in November. When the Navy took over the coastal antisubmarine mission in August 1943, the squadron moved to the western United States, where it formed the cadre for the 493rd Bombardment Group and was redesignated as the 863rd. It moved to England in the spring of 1944 and participated in the strategic bombing campaign against Germany until April 1945. It returned to the United States and was inactivated in August 1945.

The 493d Bombardment Group is a former United States Army Air Forces unit that was assigned to the 92d Bombardment Wing during World War II. It the last bombardment group to be assigned to Eighth Air Force. It flew combat missions in the strategic bombing campaign against Germany until shortly before V-E Day, then returned to the United States for inactivation. In 2002, the group was converted to provisional status as the 493d Air Expeditionary Group and assigned to Air Mobility Command to activate or inactivate as needed.