Dennis was drafted into the United States Army. He did, his basic training at Fort Louise, WA., near Seattle. Dennis completed advanced infantry training. He was then sent to Fort Benning, GA., for more training to become an infantry instructor. He then was at Fort Ord, Calif., where he was sergeant, seeing troops through their advanced infantry training, which was part of the Bravo Company. Dennis did see active duty during Vietnam. He was an ES Sergeant combat Squad Leader, in charge of and responsible for the lives of his 12 men. Dennis received his honorable discharge from the Army after serving two years.