After graduating from high school in 1946, Lieutenant General Bernard Trainor enlisted in the U.S. Marine Corps. He attended the College of the Holy Cross in Massachusetts, and then was commissioned a Marine second lieutenant after his graduation in 1951. In December of that year, he was assigned to the 1st Battalion, 1st Marines Division, 1st Marines in Korea as infantry platoon commander. Following his time in Korea, General Trainor served as executive and commanding officer aboard the USS Columbus (CA-74). Trainor would also play a crucial role in Vietnam, where he was assigned as advisor to a Vietnamese special operations group. General Trainor would eventually receive the Distinguished Service Medal, two Legions of Merit, and a Bronze Star.