Complex sentence: Elevated to Captain/Coach in 1939, Quinn led Port to a premiership in his first year as coach before the start of World War II led many of his leading players to quit football to enlist in the Armed Forces.
Split into simpler sentences: Elevated to Captain/Coach in 1939, Quinn led Port to a premiership in his first year as coach. The start of World War II led many of his leading players to quit football to enlist in the Armed Forces.