William A. Tilllam, Jr. was born in Watkins Glen in upstate New York. After graduation from high school, he enrolled in New York State Merchant Marine Academy at Fort Schuyler, The Bronx in 1940. The joined the engineering program, and almost immediately after graduation from For Schulyer, he was called up to serve with the United States Navy. After the war, he studied engineering at Syracuse University and had a career as an engineer with General Electric Co. for a quarter of a century.
During the Second World War, he was a lieutenant and the chief engineer on the USS Abner Read. The ship – a destroyer – was sunk in the Battle of Leyte Gulf in November 1944. Prior, the ship was severely damaged by a mine near Alaska; he received a commendation for helping get the ship back to port after the mining.