He helped many victims of the Nazis in occupied France, including Catholic philosopher Dietrich von Hildebrand. In 1943 he was arrested and incarcerated at the Dachau concentration camp where he assisted other prisoners during a typhus epidemic and was infected himself. When Dachau was liberated he was still aiding the sick and the last to leave.
He was made minister of the Army by Charles de Gaulle in 1946.
He served as Minister of Justice from 1959 to 1961.
Michelet was the main collaborator of Abraham Vereide, the leader of the Family fundamentalist organisation, based in the United States .