The Advanced Redoubt is trapezoid with two long unequal sides with the shortest side toward the landward direction of attack. The Redoubt has a dry moat with a drawbridge to the entrance, but unlike Barrancas the moat completely surrounds the fort. The redoubt was designed to make a landward assault by foot soldiers as costly as possible. The outer walls of the moat feature rifle ports that would create a deadly crossfire. The ramparts mounted fifteen guns.