Sovereign Harbour - Eastbourne
Between 1804 and 1812 the British authorities built a chain of towers based on the original Corsican Mortella tower, to defend the the south and east coast of England, Ireland Jersey and Guernsey against possible Napoleonic invasion. A total of 103 were built in England, along the coast from Seaford to Aldeburgh.
They stand up to 40 feet high and typically had a garrison of one officer and 15–25 men. Their round structure and thick walls of solid masonry made them resistant to cannon fire, while their height made them an ideal platform for a single heavy artillery piece, mounted on the flat roof and able to traverse, and hence fire over, a complete 360°. They became obsolete with the introduction of more powerful artillery. Many have survived to the present day, often preserved as historic monuments.
The towers had walls 8 feet thick. Entry was by ladder to a door 10 feet from the base. The walls had narrow slits for defensive musket fire. A well or cistern within the fort supplied the garrison with water and an internal drainage system linked to the roof enabled rainwater to refill the cistern.
The effectiveness of Britain's Martello towers was never actually tested in combat against a Napoleonic invasion fleet. They were, however, used later in hindering smuggling.
A number have been converted to dwellings - not easy as they are mainly listed buildings, so little externally can be altered. This is something of a blessing as can be seen from the pre-listed example in Hythe. Rather in the same way that oast houses never look right with windows, Martello towers should be left well alone.