Grant's father wrote to Representative Thomas L. Hamer requesting that he nominate Ulysses to the United States Military Academy (USMA) at West Point, New York. Despite political differences with Jesse Root Grant, Hamer, a Democrat, nominated his 17-year-old son to West Point in spring 1839. Grant was accepted on July 1, although he doubted his academic abilities. Hamer, unfamiliar with Grant, submitted an incorrect name to West Point. On September 14 Grant was enlisted Cadet "U.S. Grant" at the national academy. His nickname at West Point became "Sam" among army colleagues since the initials "U.S." also stood for "Uncle Sam".