The Chatham Ring Fortress, built from the 1870's, consisted of seven forts in an arc from Twydall, east of Gillingham to Borstal, south of Rochester. It was the last of the Ring Fortresses to be built in the United Kingdom. Passing anticlockwise they were Woodlands Redoubt (1885), Grange Redoubt (188?), Fort Darland (1899), Fort Luton (1892), Fort Horsted (1889), Fort Bridgewoods (1884) and Fort Borstal (1883). Built over a period of 25 years, they demonstrate some of the radical changes taking place in British Land Fortress doctrine. The Forts at Chatham illustrate the evolution of these changes from moveable armaments to fixed guns and were innovatory in the use of concrete in their structures. Yet improvements in gunnery saw them out of date by their completion and since the Second World War only three have survived in a complete state, Forts Borstal, Horsted and Luton. Fort Bridgewoods has been completely demolished, Woodlands and Grange Redoubts both severely damaged, while Fort Darland survives as some masonry and earthworks in a housing estate [1].

<1> Victor Smith and Ron Crowdy, 1994, From Tudor Rose to Mushroom Cloud. The Gazetter of Defence Heritage Sites in the Kentish Part of the Thames Gateway. An Overview (Unpublished document). SKE12458.