His first duty assignment was as a battery officer with the 18th Defense Battalion at Camp Lejeune. In April 1944, First Lieutenant Beckington became a platoon commander and, later a battery executive officer and battery commander with the *18th Antiaircraft Artillery Battalion. From June 1944 until January 1946, he served with the battalion on Tinian and Saipan in the Pacific. Returning to the United States with the battalion in February of that year, he remained with the unit until March 1946.