Fort Amherst, in Kent, England, was constructed in 1756 at the southern end of the Brompton lines of defence to protect the southeastern approaches to Chatham Dockyard and the River Medway against a French invasion. Part of it is now open to the public. The primary purpose of all the Medway fortifications was the defence of the Naval Dockyard. Land was acquired by two Acts of Parliament in 1708 and 1709. The land was surveyed in 1715 by the Duke of Marlborough.