Details of his military service are sketchy as Rossi rarely talks about it. He served in the Vietnam War and rose to the rank of Sergeant Major before retiring from the Corps; based on the backstory timelines, specifically the time in service required to rise to the rank of sergeant major and retire, he presumably served in the Marine Corps Reserve after joining the FBI. In the Season 8 episode "The Fallen", Rossi encounters his old unit commander, Sgt. Harrison Scott (Meshach Taylor), who has since become a homeless alcoholic living on the streets of Santa Monica, California. Through flashbacks, it is shown that Scott had saved Rossi's life in Vietnam when Rossi froze at an oncoming Viet Cong soldier. It is implied that they both served in the 1st Marine Division.
