The primary purpose of all the Medway fortifications was the defence of the Naval Dockyard. This was largely the result of the Raid on the Medway in 1667 when the Dutch fleet inflicted heavy damages on the dockyard. Defences were planned for the dockyard from 1708 and land was then acquired by two Acts of Parliament in 1708 and 1709. The land was surveyed in 1715 by the Duke of Marlborough. The first plan of defences was an enceinte (ring of fortifications), from Gun Wharf, Chatham, to north of the village of Brompton.