In February of 1943, there was a draft. Thornbrugh was drafted into the military at that time. He became a flight engineer and never had to fight in combat throughout World War II, the Vietnam War, and the Korean War.
As a flight engineer he assisted the pilots. During all those wars he flew transport, cargo, bombers (B-29s), and charter. He has been in 100 different countries. Of those his favorites were Australia, Holland, England, Italy, Germany, and Japan. He has also been around the world twice and has privately owned three small airplanes.
In relation to World War II, Thornbrugh said it "broke up families, which broke up society." This was because so many young men died during the war and that caused families to part.