Model of a ‘Carriage Garrison Disappearing BL 6inch Mark IV

Disappearing Gun Model, Royal Carriage Department, 1891

This exquisite working model of a ‘Disappearing Gun’ was built by the Royal Carriage Department at Woolwich in 1891. Designed to demonstrate the innovative mechanism invented by Captain Scott-Moncrieff, it features cast brass arms, a polished mahogany barrel, and a forest of gears and pistons below a slotted steel splinter canopy. When operated, the gun rises to fire and recoils back into its pit — a clever feat of Victorian engineering.

Scott-Moncrieff first proposed the idea of the ‘Disappearing Carriage’ in 1865. Rather than leaving the gun exposed on a fixed mount, he hid it in a pit behind a simple parapet, mounted on two long arms with a counterweight. Firing released the counterweight and swung the gun upward; recoil sent it back down to be reloaded. This ingenious design saved on stone and iron, and concealed the gun's location until the moment of firing. Later versions used hydraulic pistons to manage recoil and re-elevation.

The invention took shape just as fears of a French invasion were mounting. In 1859, the French Navy launched the powerful ironclad Glorie, challenging Britain’s naval supremacy and raising fears of invasion. The government swiftly convened a Royal Commission on the Defence of the United Kingdom, which by 1860 proposed a vast programme of coastal fortifications. Though one ship did not launch a thousand forts, the estimated cost reached £11.85 million — around £1.45 billion today.

Construction of Portsmouth’s ring of forts — the so-called ‘Palmerston’s Follies’ — began in 1865, the same year as Moncrieff’s submission. His disappearing gun design offered a more efficient, less costly alternative, and it was eventually adopted across the British Empire. A full-size example survives at Lei Yue Mun Fort, now home to the Hong Kong Museum of Coastal Defence.

Ironically, by the time many of these grand defences were completed, the threat they were designed to meet had already faded. France was defeated by Prussia in 1871, and with it went the fears of a Gallic invasion.