Complex sentence: Fort Riviere was a mountain fort on the summit of Montagne Noire, on the north coast of Haiti, located to the south of Grande-Rivière-du-Nord and 20 miles south of Cap-Haïtien.
Split into simpler sentences: Fort Riviere was a mountain fort on the summit of Montagne Noire. It was located on the north coast of Haiti and to the south of Grande-Rivière-du-Nord and 20 miles south of Cap-Haïtien.