 She was captured by the Gestapo and spent a year as a prisoner of war, later writing a book about her experiences.She also wrote a book about one of her brothers, General Billy Mitchell, who is regarded as the founder of the U.S. Air Force.Ruth Mitchell was born 30 April 1889 in Milwaukee, Wisconsin, the daughter of Harriet Danforth (Becker) Mitchell and John Lendrum Mitchell, who a few years later would become a U.S. congressman and senator.