Complex sentence: Left a sealed envelope from Jethro De La Poer, he learns of his uncle's tragic death-upon a boat trip return to New England, a crash on the shore killed Jethro's wife and son.
Split into simpler sentences: Left a sealed envelope from Jethro De La Poer, he learns of his uncle's tragic death. Upon a boat trip return to New England, a crash on the shore killed Jethro's wife and son.