From World War I through World War II, Italian Navy engineers were at the vanguard of special maritime operations. From the use of combat divers to the development of weapons, Italian naval expertise knew no rival in unconventional littoral combat. An example of their special warfare prowess started in the closing weeks of World War I when a rudimentary limpet mine sent to the bottom the Viribus Unitis.
Italian naval commandos, astride a converted torpedo, silently moved into Croatia's Pula harbor with the goal of sabotaging an Austrian ship. They set their sights on a dreadnought, Austria's flagship Viribus Unitis.
The two Italian frogmen and their modified German torpedo penetrated harbor defenses on the night of October 31, 1918. In the nose of the torpedo, a pair of 400 lbs demolition charges. Initially the plan was to swim into an Austrian held harbor and afix a charge. However, when a German 'dud' torpedo washed ashore along the Italian coast, it was converted and became the combat divers chariot, a nickname that stuck for many manned mini-submersibles.
Moving into the harbor, the combat swimmers and their torpedo made their way to the waterline of the Viribus Unitis. What they did not know was that the crew of the Austrian battleship, and remainder of the fleet, had mutinied and were now under command of a Yugoslavian officer.
Carefully putting the charge on the hull, the two frogmen began to motor away but were quickly discovered by sentries. Taken to the very ship which they mined, the two Italian saboteurs told the captain that it was nearing dawn and before 7 a.m. a charge would go off and sink the battleship.
After some doubt and haranguing, a portion of the ship's crew left the ship. However when the expected 6:30 a.m. charge failed to go off, doubt in the frogmen and those in boats out on the water increased. Back on board were the Italians and several hundred Yugoslav crewmen who replaced the mutinied Austrians.
And then 6:44 a.m. a low thud was heard coming from the water. A split second later, a column of water shot up and the Viribus Unitis began to list and sink. It would take 15 minutes but the Austrian flagship would sink, taking her captain and 300 crewmembers with her.
A simple 400 pound charge brought to the bottom a 21,000 ton dreadnought.
Next week we'll examine the British limpet mine and the attacks launched by Allied forces during World War II.