Complex sentence: His second marriage, to Jane Mitchum, was of dubious validity because it occurred 23 days before his divorce from Barton was final, lasted for four years, from September 1953 to October 1957, the couple had two children.
Split into simpler sentences: His second marriage, to Jane Mitchum, was of dubious validity because it occurred 23 days before his divorce from Barton was final. It lasted for four years, from September 1953 to October 1957; the couple had two children.