 Sandgate Castle was still in use during the Napoleonic Wars at the start of the 19th century, but was heavily rebuilt. Brigadier-General William Twiss surveyed the south coast in 1804, and proposed building a series of 58 new defensive towers along it, as part of which he proposed converted Sandgate into a "secure sea battery". After some opposition, and many delays within the War Office, the work on the castle finally began in 1805.
