 In June 1960, Kelley joined the United States Navy through the Officer Candidate School program in Newport, Rhode Island.After assignments as a surface warfare officer on and , he volunteered for service in Vietnam as a lieutenant in command of River Assault Division 152, part of the Mobile Riverine Force.On June 15, 1969, Kelley led eight river assault craft boats on a mission to extract a United States Army infantry company from the bank of the Ong Muong Canal in Kien Hoa Province, South Vietnam.