 The following year, Stewart garnered his first of five Academy Award nominations for his portrayal of an idealized and virtuous man who becomes a senator in Capra's "Mr. Smith Goes to Washington" (1939).He won his only Academy Award for Best Actor for his work in the screwball comedy "The Philadelphia Story" (1940), which also starred Katharine Hepburn and Cary Grant.A licensed amateur pilot, Stewart enlisted as a private in the Army Air Corps as soon as he could after the United States entered the Second World War in 1941.