President Harry S. Truman appointed him U.S. representative to UNESCO in 1946, although he retired to Concord shortly after to write his memoirs.
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Winant committed suicide in 1947 in his Concord home[12] on the day his book Letter from Grosvenor Square was published,[13] and was buried at St. Paul's School. The 2010 book reports that after Roosevelt's death, with Winant's distance from his Republican Party base, "[h]e hoped that he was going to become secretary-general of the new U.N. .... On top of that [disappointed hope], his affair with Sarah Churchill ended badly. 'He was an exhausted, sick man after the war,'" author Olson continued in the interview on NPR.[10]