Textile manufacturing Racehorse owner/breeder Known for Man o' War , War Admiral Samuel Doyle Riddle (July 1, 1861 – January 8, 1951) was an American businessman and racehorse owner. He was born in Glen Riddle , Pennsylvania , a small town southwest of Philadelphia given the family name by his father. Samuel D. Riddle, a native of Delaware County , owned and operated a woolen mill