Who's to say that among the American generals in WWII there wasn't at least one with the name Grant?
General Grant may have died by the time of the Second World War, but Simon Bolivar Buckner, Jr., son of Grant's friend from West Point days, won the last battle of the war, the battle of Okinawa. At least in the sense that he was in command--the troops involved in the battle actually won it.
Kind of like confusing the My Lai Massacre with the Battle of Mylae.