The Brigand(1952)

Carlos Delargo, the banished son of a royal princess of Mandorra, is returned to the kingdom to be tried for a murder change. However, he is freed by King Lorenzo, whom bears a remarkable resemblance to Delargo. When the king is wounded by assassins sent by Napoleon, Delargo takes over the throne at the request of the Prime Minister in a plot to thwart the traitors. He also falls in love with Princess Teresa, the king's fiancée.