Marshall Field III was born in Chicago, on 28th September, 1893. His grandfather, Marshall Field, was an extremely wealthy businessman and he was sent to be educated at Eton College and the University of Cambridge.
After the war he worked as a bond salesman before joining Charles F. Glore and Pierce C. Ward to form the investment banking firm of Marshall Field, Glore, Ward & Company. Field became extremely wealthy after receiving a significant proportion of his grandfather's $118 million estate.
Field was a strong supporter of Britain in the Second World War. He worked closely with the administration of President Franklin D. Roosevelt and Fight for Freedom, an organization established by the British Security Coordination. In October 1941 Field started the Chicago Sun to counter the isolationist policy of Colonel Robert McCormick, who owned the Chicago Tribune. According to Field's editor, Turner Catledge: "It was early in 1941 that Field resolved to start a newspaper... Roosevelt was trying to move the nation toward support of England and Colonel McCormick was fighting him tooth and nail... The Tribune's influence on the American heartland was great, and to Field and others who thought the United States must fight Nazism, McCormick's daily tirades were agonizing."
Walter Trohan argues in his autobiography, Political Animals: Memoirs of a Sentimental Cynic (1975), that J. Edgar Hoover and the FBI became involved in this project: "In order to help the paper get an Associated Press franchise, then a guarded possession, FDR had FBI agents call upon various small-town publishers and urge them to support Field's bid for a franchise. J. Edgar Hoover, head of the FBI, later showed me the order he had received to undertake a campaign, which he considered above and beyond his unit's functions."
Marshall Field III died of brain cancer on 8th November, 1956.