After receiving his Ph.D. (1900) from Harvard University, Fay studied at the Sorbonne and the University of Berlin, returning to teach history at Dartmouth (Hanover, N.H.) and Smith (Northampton, Mass.) colleges and at Harvard and Yale universities until his retirement in 1946.
Fay was the first U.S. historian to challenge the widely held notion that Germany alone was responsible for initiating World War I. His Origins of the World War, 2 vol. (1928), resulted from his exhaustive study of previously uninvestigated archives and documents. He proposed the thesis of collective responsibility for the outbreak of war, placing blame on Serbia’s independent role in the assassination of Archduke Francis Ferdinand (June 28, 1914), on Austrian demands, on German support to Austria-Hungary, on Russian mobilization, and on French and English compliance with Russia. Fay’s book was thus extremely influential in modifying attitudes toward Germany after the war.
Fay is also considered one of the most eminent American authorities on German history, particularly the rise of the Prussian state. His other major works are The Hohenzollern Household and Administration in the Sixteenth Century (1916) and The Rise of Brandenburg-Prussia to 1786 (1937). He also translated Friedrich Meinecke’s Die deutsche Katastrophe (The German Catastrophe) in 1950.