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Photo Feature - The Moncrieff Counterweight Disappearing Gun

Crownhill Fort, Plymouth, England

Crownhill Fort was designed by Capt.E.F. Du Cane as the principal, and largest, fort of Plymouth's North-Eastern Defences, designed to defend the Royal Naval Dockyard at Devonport from an attack by the French from the north of the city. Designed and built as one of the country's later Palmerston forts, Crownhill represented the cutting edge of fortress design in the theory, and materials, used in its construction. It was constructed on a knoll 400 metres in front of the defensive line and as this was an exposed position, the Fort is designed for all round defence unlike that of any other fort in the Plymouth defences. The Fort has seven sides, all with massive ramparts, surrounded by a deep dry ditch with each flank defended by gunfire from projecting caponiers....

The Moncrieff Counterweight Disappearing Gun

The gun used a counterweight system which, when after loading, a brake was released. This would then release a counterweight which would move the gun above the parapet where it would fire. The recoil (and the counterweight) would then bring the gun below the parapet for reloading again.. Captain Colin Moncrieff, the gun's inventor, had the clear intention that (apart from the large amount of smoke generated!) the gun and its crew would effectively remain invisible to an attacker, making it virtually impossible to 'draw a bead' on the emplacement from the sea (where the greatest threat was perceeived). An interesting concept, and can be seen from the photos, an impressive piece of engineering!

The End of the 'Land Battleship' Concept

By the end of the 19th Century, the continued advances in artillery (particularly in Naval Artillery) had made the fortresses of this type obsolete. The introduction of armor on board warships and the creation of the 'Dreadnought' class of warship had created a new form of warfare. Crownhill Fort was fortunately never used as was intented in its concept. Only years later, did it first fire its guns in anger - as an AA position, protecting the City of Plymouth and its vitally important Naval Dockyards from an enemy inconceivable to the military architects of the 19th Century - the Luftwaffe.....