The idea of this type of combat torpedo was furnished from previous manned torpedo actions that occurred in World War One. However, it was the Italian Decima MAS, 10th Light Flotilla, formed in 1940, that perfected this type of underwater warfare. The 10th Light Flotilla was responsible for 28 ships sunk or damaged in World War Two, including the battleships HMS Queen Elizabeth, HMS Valiant, cruiser HMS York and over 100,000 tons of merchant shipping.
The Decima MAS frogmen were not only deadly, but also very ingenious in their methods of attack. The feats of these Italian frogmen brought much envy and respect from the British Navy, who had to develop their own scuba team to combat the Italians. It is rumored that when the British created its own naval assault units, the trainees placed pictures of Decima MAS on their walls for inspiration. Winston Churchill went on record recognizing Decima MAS for their "Extraordinary courage and ingenuity."
The unit is the forerunner of all international underwater combat units including the US Seal Teams.