Complex sentence: War Admiral had just been defeated by Seabiscuit in their famous match race at Pimlico Race Course just 11 days earlier and owner Samuel D. Riddle chose the Rhode Island Handicap for the star's next race.
Split into simpler sentences: War Admiral had just been defeated by Seabiscuit in their famous match race at Pimlico Race Course just 11 days earlier. Owner Samuel D. Riddle chose the Rhode Island Handicap for the star's next race.