Meanwhile, on the continent, the art of fortification had become a science with its own technical language - escarpment, ravelin, caponier, rampart, glacis and casernate, words not common in England until the resurgence of the French navy in the 1850s forced a worried British government into frantic fortress building. Defence works sprung up around the new harbour at Portland. Rearmed in the 20th century with modern breech loading guns they were reinforced by batteries on the coast at Upton covering Weymouth Bay and Blacknoor overlooking Lyrne Bay.

The era of the guided missile saw the end to the active service of these fortresses and batteries. Most have become derelict with the notable exceptions of the Nothe Fort at Weymouth, now a successful and very interesting visitor attraction, and the Verne Citadel on Portland which has been turned into a prison.