Midget submarines present an ongoing challenge to modern naval forces. Almost impossible to detect in the vast expanse of the ocean, they can spy on military movements, penetrate harbour defences, lay mines, launch torpedoes and disrupt passage through vital channels. The Iranian military was recently reported to have developed its own to deny access to the Persian Gulf.

Tiny vessels with a long history

But tiny undersea vessels have a long history, and the "human torpedoes" developed for use during World War II were every bit as perilous to their crew as the name suggests.

The first was developed by Italy and quickly nicknamed Maiale, or "pig", by sailors due to its cumbersome steering. Electrically powered, it would be launched from a submarine or ship crewed by two sailors in diving suits, who would steer it towards a target, such as a ship in harbour, and attach a limpet mine before sailing to safety.

The concept proved so successful the British and German navies developed their own versions.

Restored to its former glory

One of these unique vessels is currently under restoration at the Imperial War Museum's Duxford site. In this Latest In Defence video, conservation manager Chris Knapp talks us through the work he and his team are undertaking to restore it to its former glory, while showing off its gleaming brass and wooden interior to best effect.

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