Complex sentence: Fifteen of these films were with the director John Ford, commencing with "The Prisoner of Shark Island" (1936), which was produced when both men were working at the 20th Century Fox studio.
Split into simpler sentences: Fifteen of these films were with the director John Ford. Their collaboration commenced with "The Prisoner of Shark Island" (1936), which was produced when both men were working at the 20th Century Fox studio.