Complex sentence: Today known as Farrars Island, some were surrounded by about seven miles (11 km) of the James River, with a wide neck, which was soon protected with a palisade and moat-like ditch.
Split into simpler sentences: Today known as Farrars Island, the site comprised with a shoreline of seven miles (11 km) on the James River. It had a wide neck connecting to the shore, which was soon protected with a palisade and moat-like ditch.