The Raid on the Medway during the Second Anglo-Dutch War in June 1667, sometimes called the Battle of the Medway, Raid on Chatham or the Battle of Chatham, was a successful and daring attack conducted by the Dutch navy deep upriver targeting the largest English naval battleships at a time when most were virtually unmanned and unarmed, laid up due to lack of funding in the fleet anchorages off Chatham Dockyard and Gillingham in the county of Kent. At the time, the fortress of Upnor Castle and a barrier chain called the 'Gillingham Line' were supposed to protect the mothballed naval ships anchored off Chatham, the main English naval base in southeastern Stuart England.