A 1940 graduate of the Naval Academy, Michaelis reported to the fleet flagship USS Pennsylvania (BB-38) and became involved in an early installation of radar. After surviving the attack on Pearl Harbor, he went to flight training in Pensacola and qualified as a naval aviator. In the latter part of World War II he was in Fighter Squadron 12 (VF-12), which he eventually commanded. After postgraduate education in aeronautical engineering, he was involved in nuclear weapons development, commanded Air Group 11 in the USS Kearsarge (CVA-33), served on the AirPac staff and with the Assistant Secretary of the Navy for Air. He was executive officer of the USS Randolph (CVA-15), skipper of the oiler USS Tolovana (AO-64), underwent nuclear power training, served in the Plans and Policy section of OpNav, and in 1963 became second CO of the nuclear-powered carrier USS Enterprise (CVAN-65). As a flag officer he was ComCarDiv 9, on the staff of DCNO (Air), as deputy of the Joint Strategic Target Planning Staff, as Commander Naval Air Force Atlantic Fleet from 1972 to 1975, and finally as the four-star Chief of Naval Material from 1975 until his retirement in 1978.