Complex sentence: He married Jean Williamson in September, 1939, a woman he had first met in 1926 when she was 13.She died in December 1992 In his youth he was a keen tennis player, recording in his diaries how many sets he played each day.
Split into simpler sentences: He married Jean Williamson during September, 1939, a woman he had first met during 1926 when she was 13 years old. During his youth he was a keen tennis player, recording in his diaries how many sets he played each day.