Portland's Inner Pierhead Fort is a Victorian fort built to defend Portland Harbour. The fort is situated on the end of the inner breakwater, which abuts from the dockyard of the harbour, on the northern face of the island. It was constructed between 1859-1862, and is 100ft in diameter. In September 1978 the inner breakwater became Grade II Listed, and this designation includes the fort.
John Coode, resident engineer of the breakwaters, remained undecided on whether the fort should be built with Portland stone or granite. Before construction could begin, Coode had the army build two butt walls, one of Portland stone, and the other granite during September 1859. HMS Blenheim was ordered to use heavy fire upon these walls from a distance of 450 yards. Portland stone proved to be stronger during the trial, and was therefore chosen as the building stone.
Information by kind permission of Portland History © Ashley Smith