The Château Vert stood opposite the Château d'Espérance at the head of the east jetty. Like its neighbour, the Château Vert was a wooden fort supported by stilts on a base of pilings. It was longer and narrower than the Château d'Espérance and most of its guns did not face out to sea, but to the east. The reason for this was to cover the area to the east of the jetties, from which ships could bombard the town. As with the Château d'Espérance, the rear of the fort was protected by two demi-bastions of loopholed walls, with a bridge leading to the jetty.
The Anglo-Dutch attacks on Dunkirk in the 1690s all came from the west, so only the north-facing guns of the Château Vert were used. The attackers sent fireships against both the forts at the jetty heads, but the heavy fire coming from both forts forced their crews to set them on fire while they were still a long way off, so none of them reached the forts. During the 1695 bombardment the Château Vert was hit by a shell from a bomb vessel, which did no damage apart from making a hole in the fort.