Midget submarine

A midget submarine (also called a mini submarine) is any submarine under 150 tons. Typically operated by a crew of one or two but sometimes up to 6 or 9, with little or no on-board living accommodation, they normally work with mother ships, from which they are launched and recovered, and which provide living accommodation for the crew and other support staff.

Both military and civilian midget submarines have been built. Military types work with surface ships and other submarines as mother ships. Civilian and non-combatant military types are generally called submersibles, and normally work with surface ships.

Most early submarines, such as the United States Navy's Holland and the British Royal Navy's Holland 1, would now be considered midget submarines.

Midget submarines are best known for harbor penetration, although only two World War II boats, the British X-craft and the unsuccessful Welman submarine, were specifically designed with this in mind. Japan's Ko-hyoteki-class submarines were originally designed to take part in decisive fleet actions. However, as circumstances changed, they ended up given the task of harbor penetration. Germany’s various World War II designs were mostly designed to attack Allied shipping off landing beaches and harbors, although the Seehund had a great enough range to attack shipping off the Thames estuary.

Midget submarines have also seen some use in support roles. X-craft were used for reconnaissance, and the Seehund was used to carry supplies. A number of modern midget submarines have also been built for submarine rescue.

Midget submarines are commonly armed with torpedoes and mines in the form of, for example, detachable side loads and nose sections. Alternatively they may function as swimmer delivery vehicles to deliver frogmen to the vicinity of their targets, which are then attacked with limpet mines.

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