Step 1 : Introduction to the question "For which film did John Wayne win his only Oscar?"
John Wayne won his first and only acting Academy Award in 1969 for his role in True Grit. He played U.S. Marshal Rooster Cogburn, an eye-patching drunkard and lawman, who helps a young woman named Mattie (Kim Darby) track down her father's killer. A young Glen Campbell joined the pair on their mission. Rounding out the cast, Robert Duvall and Dennis Hopper were among the bad guys the trio had to defeat. Upon accepting his Oscar, John Wayne said, "Wow! If I'd known that, I'd have put that patch on 35 years earlier."