Complex sentence: The Main Gate of the fort, regarded as the weakest part of any fortification, is set in the center of the North West Casemates and embrasures in those Casemates permit defenders to fire directly on any attackers in the ditch in the vicinity of the gate.
Split into simpler sentences: The main gate of the fort, regarded as the weakest part of any fortification, is set in the center of the north west casemates. Embrasures in those casemates permit defenders to fire directly on attackers in the ditch in the vicinity of the gate.