Complex sentence: The Parliamentarians reinvested the place but by the middle of November threatened by a Royalist army and his besieging force decimated by disease Weller ended the investment five days later on 20 November Gage arrived with fresh supplies.
Split into simpler sentences: The Parliamentarians reinvested the place but by the middle of November threatened by a Royalist army and his besieging force decimated by disease Weller ended the investment. Five days later on 20 November Gage arrived with fresh supplies.