Carlton Joseph Huntley Hayes (May 16, 1882 – September 2, 1964) was an American historian, educator, diplomat, devout Catholic and academic. A student of European history, he was a leading and pioneering specialist on the study of nationalism. He was elected as president of the American Historical Association over the opposition of liberals and the more explicit Anti-Catholic bias that defined the academic community of his era. He served as United States Ambassador to Spain in World War II. Although he came under attack from the CIO and others on the left that rejected any dealings with Francoist Spain, Hayes succeeded in his mission to keep Spain neutral during the war. Life and career Hayes was born to a Baptist family in upstate New York, the son of Permelia Mary (née Huntley) and Philetus Arthur Hayes. He graduated from Columbia College in 1904. In 1903 he became an active member of his fraternity, Alpha Chi Rho, he remained an involved member over his lifetime. He earned his Ph.D degree at Columbia in 1909 with a thesis on the Germanic invasion of the Roman Empire. The thesis, ""An Introduction to the Sources Relating to the Germanic Invasion," which was supervised by James Harvey Robinson, was published by Columbia University Press in 1909. He became lecturer at Columbia in European History in 1907, then was promoted subsequently to assistant professor (1910), associate professor (1915), and full professor (1919). Historian In 1904 he converted to Catholicism, and later went on to be the first Roman Catholic co-chairman of the National Conference of Christians and Jews alongside Everett Clinchy and Roger Williams Strauss, serving as co-chairman 1928 to 1946 despite a 1928 papal encyclical which explicitly prohibited such ecumenical interactions. He was chairman of Columbia's History department several times. After World War I, he joined with Peter Guilday in establishing the American Catholic Historical Association and became its first secretary. Its goal was to promote Catholic history and to integrate Catholic scholars into the wider academic world. Hayes was influenced by Charles A. Beard, a proponent of the "New History", which emphasized the importance of cultural economic developments as opposed to just warfare and diplomacy. Hayes argued the New History demonstrated that Original Sin was integral to human existence. His two-volume Political and Cultural History of Europe, long a major textbook, is filled with examples of such thought, none more so than his discussion