Oh, and for military nauticalia, of course the Chatham dockyard heritage site, and for stuff from the Napoleonic wars, Fort Amhurst also in Chatham. More military nauticalia in Upper Upnor (there used to be a chain across the Medway there to protect the Chatham naval base, breached by the Dutch in (?) the early 1700s (this date could be up to 100 years out, history not my favourite subject). Gravesend also has a museum in a gun emplacement in the FOrt Gardens - also sacked by the Dutch at about the same time.