American historian of architecture whose research ranged from an initial focus on the Italian Renaissance to evolutionary theory and computer modelling. Hersey was born in Cambridge, Massachusetts, the son of Milton Leonard Hersey (1899-1983), an economist, and Katharine Hersey (Page) (1896-1991). After graduating from high school in 1945, Hersey joined the merchant marine where he assisted in transporting troops home after World War II. Following this, Hersey joined the U.S. Army, where he advised returning war veterans in planning for their future.