Complex sentence: In September 1874 "HMS Rosario" under the command of Captain Dupuis arrives to investigate the claims against Hayes, who is arrested but then escaped in a 14 foot boat, built of timber from the wreck of the "Leonora".
Split into simpler sentences: In September 1874, "HMS Rosario" (under the command of Captain Dupuis) arrived to investigate the claims against Hayes. He was arrested, but then escaped in a 14 foot boat, built of timber from the wreck of the "Leonora".