Plot: Rising out of the Solent, one mile off shore, like a silent sentinel, Spitbank Fort was constructed between 1861 and 1878 as one of Palmerston's Follies, a series of land and sea-based forts designed to repel French invaders during the Napoleonic Wars. Spitbank Fort was the last of four, fully armoured forts to be constructed to defend the Solent yet, ironically, by the time they were completed, the risk of invasion had passed