Following graduate studies at the University of Michigan, he served until 1957 as project officer on the TM-61B Matador weapon system in the Directorate of Systems Management, Headquarters Air Research and Development Command, Wright-Patterson Air Force Base, Ohio.

In January 1960 he was appointed chairman of the configuration control board for the Atlas ballistic missile program.

In August 1964 he entered the Industrial College of the Armed Forces at Fort Lesley J. McNair, Washington, D.C.

Bellis became the commander of Sixth Allied Tactical Air Force with headquarters at Izmir, Turkey, in June 1977.

He assumed the position of vice commander in chief, US Air Forces in Europe on 27 July 1978.