The Underwater Assaulters: the secret weapon of the Royal Navy in the Second World War

(To Tiziano Ciocchetti)

The personnel employed in the Regia Marina Grouping of Assaulters (first in the 1ᵃ Flottiglia and subsequently in the Xᵃ MAS Flotilla) was divided into two main branches: surface assemblies (intended to work with the boats) and those underwater (in turn subdivided in assault swimmers and depth assaulters equipped with SLC).

The training was long, hard and complex, since in the underwater field - as well as in the field of physiology and underwater medicine - there were no great skills but the first steps were still taking place. Consider that the very first project involved the use of Marchers, or men trained to march, with appropriate ballast, on the bottom of the ports in which the ships to be hit were moored.

However, among a thousand improvisations, difficulties and experiences experienced at the moment the small but aggressive body will be able to achieve a cohesion and efficiency such as to allow the operators to sink, using the full range of means available, well 264.872 tons of enemy vessel, between the entry into the war of the Kingdom of Italy and the armistice of 8 September 1943. To be precise, two battleships, a cruiser, two destroyers, 4 tankers and 23 steamers were sunk, or otherwise put out of order.

In the attack on the port of Alexandria, Egypt was used Slow-Stroke Torpedo, or a normal torpedo for submarines from 533 mm and long 6,70 meters, which had been modified to allow a crew of two men to easily maneuver using it as a means of transport for themselves and for a large explosive charge. First of all, the engine and the special batteries that allowed the torpedo to reach a speed of several tens of nodes were removed, and had been replaced with a less powerful engine and a 30 battery, elements capable of supplying a total voltage of 60 volt. By means of a handwheel rheostat the pilot, who sat astride the device in the front position, regulated the power supply of the engine thus varying the speed up to a maximum of about 5 km / h.

Immediately behind the war head and at the stern there were two trim crates which, filled or emptied by the introduction or exit of compressed air contained in cylinders, allowed to control the torpedo as a mini submarine. Behind the pilot was the other operator, mainly responsible for the operations of fixing the explosive head and the removal of any obstructions and parasilus networks. The head, long 1,80 meters, contained 300 kg of explosives; it was equipped with two timepieces and a self-destruct device, a device that was also found in the driving section of the vehicle.

The maximum duration of the spooling time was two and a half hours. After having mined the target the operators could move away by driving the torpedo without more explosive head, or they could sink it, after having activated the self-destruction and to save themselves reaching the shore.

(photo: web)