After teaching for nearly ten years at Wesleyan, Brandeis, and Harvard, he moved to Princeton University in 1961 where he taught until his retirement.
In 1944 he obtained American citizenship and enlisted in the United States Army where he was stationed to Fort Ritchie, Maryland due to his linguist skills. There he interrogated high-ranking German POWs.
Received a Ph.D in history from Yale University.
Earned his master's degree from the Graduate Institute of International Studies in Geneva, Switzerland.
Graduated from the City College of New York.
Fled with his family when the Nazis invaded France in June 1940. He arrived in the United States in 1941.