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Decima Flottiglia MAS

From their first triumph in March of 1941, The British were nervously on guard of a potential surprise attack by the most effective and devastating branch of the Italian military of World War Two; the 10th Light Flotilla (or Xa Mas).

The Italian Frogman

The Duke of Spoleto, who was a motor boat enthusiast, helped dream of the idea of a naval assault unit for the Italian Navy. These units utilized Explosive Motor Boats, Torpedo Boats, Miniature submarines and the infamous Human Torpedoes (AKA: SLC or Maiale). By the end of the war, these units would sink, or severely disable, 86,000 tons of Allied warships and 131,527 tons of merchant shipping.

In October of 1935, two sublieutenants proposed a radical new weapon which would eventually become known as the Human Torpedo. The Italian Navy was so excited and aware of the potential of this new weapon that they ordered a testing in La Spezia 3 months later.

The idea of a manned torpedo was furnished from previous manned torpedo actions that occurred in both the Revolutionary War and World War One. But it was the Italian 10th Light Flotilla, formed in 1940, that would perfect this deadly new weapon.

The 10th Light Flotilla was responsible for 28 ships sunk or damaged in World War Two. These ships include the battleships HMS Queen Elizabeth, HMS Valiant, cruiser HMS York and 111, 527 tons of merchant shipping.

Partial listing of ships sunk or crippled by the 10th Light Flotilla
Durham 10,900 Tons Gibraltar Sep, 1941
Baron Douglas 3,900 Tons Gibraltar July, 1942
Raven’s Point 1,900 Tons Gibraltar July, 1942
Kaituna 10,000 Tons Mersin July, 1943
Meta 1,600 Tons Gibraltar July, 1942
Camerata 4,900 Tons Gibraltar May, 1943
Stanridge 6,000 Tons Gibraltar Aug, 1943
Queen Elizabeth 32,000 Tons Alexandria Dec, 1941
Valiant 31,000 Tons Alexandria Dec, 1941
Harmattan 4,600 Tons Algiers Dec, 1942
Jervis 1,700 Tons Alexandria Dec, 1941
Mahsud 7,500 Tons Gibraltar May, 1943
Fernplant 7,000 Tons Iskenderun Aug, 1943
Empire Centaur 7,000 Tons Algiers Dec, 1942

Italian frogmen were not only deadly, but also very ingenious in their methods of attack. Known as the “Floating Trojan Horse of Gibraltar”, Italian frogmen used an imaginative method of destroying enemy ships.
Gibraltar was very tempting to the Italians for their safe shelter of British warships and allied merchant shipping. The Italian frogmen originally used a Spanish villa that was located 2 miles from Gibraltar. It was owned by an Italian officer married to a Spanish woman named Conchita Ramognino.

This villa held the frogmen who would sneak out into the harbor and attack unsuspecting British warships. But this proved very difficult and costly. The harbor was very well protected by netting, patrol boats and search lights. Because of this difficulty, the Italians decided to use a battered Italian merchant ship docked across the bay of Gibraltar. It was the 4,995 ton Olterra.

The Olterra redesigned for Human Torpedo attacks

Italian frogmen secretly replaced the crew with divers and technicians and built a workshop to house, build and maintain human torpedoes. A door was then cut 6 feet below the surface to allow these 2-man human torpedoes to come and go undetected.

Replacement torpedoes were shipped from Italy disguised as boiler tubes. When the Italian frogmen commenced their attacks on British warships from this location, it proved just as costly. Five out of six frogmen never returned. But when the Italians decided to attack the merchant shipping, which was less protected, they were rewarded with easy prey. Italian frogmen sank or damaged a total of 42,000 tons of Allied shipping.The British never did find out where these frogmen came from or where they gone.


“Everyone has the jitters, seeing objects swimming about at night, and hearing movements on ships’ bottoms. It must stop!” – Admiral Sir Andrew Cunningham, Commander in Chief of Britain’s Mediterranean Fleet.



    Its amazing what a small group of determined men can do. X MAS is such a group, an elite unit with very special skills and special weapons. There story is little known, but to those who know it is both fascinating as well as it is inspirational. An amazing story of courage and boldness with acts to be truly admired. Memento Audere Semper (Remember to dare always) X MAS, a bold and daring group.

  2. Paul Baker says:

    The History Society Gibraltar are looking into getting a plaque to commemorate the submariners both British and Italian that took part in the underwater activities in Gibraltar. I am unable to find a contact in Italy to start the ball rolling.

    I can remember the Olterra anchored some 100 meters away from the Shell tanker I was working on in the Bay in the 1950’s.

  3. Very nice web page most people think the brittish had the first frogmen no so the Italians did. I BELIEVE THEIR WAS A OLD MOVIE ABOUT LINONAL CRABB WHICH WAS VERY GOOD AND GAVE CREDIT TO THE ITALIAN AND SHOW THE LIPMENT MINES