By 1850 France, the old enemy of Britain, had recovered after defeat at Waterloo and was stretching her muscles on the world stage by building a modern fleet.

With the launch of "La Gloire", the first fully iron-clad warship, the British government became concerned, and hurriedly passed bills through Parliament to construct or modernise over seventy forts and fortresses for the defence of naval harbours - nicknamed "Palmerston Follies" after the prime minister of the day.