18th century land defences of Chatham dockyard and barracks. A bastion trace of regular form constructed in 1756. The axis of the line extends North-East-South-West across the high ground from the site of Gillingham fort to Chatham. This survives for much of its length as revetted ditch and rampart. At the south end the reconstruction of 1778 led to the provision of the "Couvre Porte" battery and Prince William's Bastion and by retrenchment to create Amherst Redoubt and Belvedere Battery. These additions gave greater enfilade fire in the moats and created a "Keep" in Amherst Redoubt. Much of these additions remain but they are now extremely overgrown. At the north end a similar reconstruction, Townsend's Redoubt has largely disappeared.