In May 1915, when the First World War was raging, Italy saw that the situation was not right and turned to side with the Entente and fought hand in hand with the British and French armies, because of Italy's position on the battlefield, Austria-Hungary became its main opponent, and the Austrian navy in the Adriatic Sea became the key blockade target.
It is not easy to completely eliminate hidden dangers at sea, the Austrian navy is cowering in the harbor under the threat of the Italian navy, but the port is protected by shore defense artillery, and it is obviously unwise to attack, the Italians thought of using torpedoes for special operations, but even if the torpedo boat secretly moves at night to avoid the blow of the shore defense artillery, it cannot pass the navigation blocking equipment set up by the Austrian side on the water, and cannot enter the effective firing range.
This took a turn for the better in 1917, when designer Attilio Bizio proposed a torpedo boat with a flat bottom, extremely low draft, and tank-like tracks, which could sail at sea like a conventional ship and climb over obstacles through the tracks, the Grillo (cricket), also known as a sea tank.
The Grillo torpedo boat is structurally similar to the landing craft of World War II, it is a wooden flat-bottomed boat, 16 meters long, 3.1 meters wide, with a draft of only 0.7 meters, a displacement of 8 tons, and a crew of 4 people. There were two low-horsepower engines, one driving the propeller to allow the torpedo boat to reach a speed of 4 knots, and the other to drive the tracked structure.
The Grillo torpedo boat was equipped with longitudinal narrow tracks on both sides, and the overall structure was similar to the over-the-top track design used by tanks at that time, with the driving wheels in the rear, and curved hooks installed at intervals on the track shoes, which could hook objects to assist in moving forward during operation, and the use of this equipment could climb over the water obstacles set up by the Austro-Hungarian Navy.
The combat armament of the torpedo boat is two 450 mm torpedoes, one tied to each of the two sides of the hull, because the torpedo boat has too short range and poor seaworthiness, so it needs the tow boat to assist in moving to the preset sea area and then independently dispatching, after turning over the obstacle, release the torpedo in the appropriate position to attack, and then immediately return to the tow boat to evacuate, of course, this process generally needs to be carried out secretly at night, otherwise it will be blown into a pile of broken wood in a few minutes if it is discovered by the shore defense gun.
A total of 4 torpedo boats of this particular type were built in Italy, because the action of jumping over obstacles was like an insect jumping, and all 4 torpedo boats received the name of an insect, the first being a cricket, the last three being a grasshopper, a locust, and a flea.
The Italian navy tried to "do something" with these torpedo boats in the latter part of World War I, and they organized several attacks, but none of these operations were successful, and they were either found by the defenders and forced to evacuate or lost.
The Austro-Hungarian navy also noticed this new feature of the Italian navy's equipment in repeated encounters, and it was impossible to know its exact performance due to the lack of accurate information, but they reacted by raising the grid height of the anti-torpedo boats and attempting to imitate the torpedo boats.
At least during the First World War, the Grillo torpedo boats were a military failure, and after the war people quickly abandoned this design in favor of conventional torpedo boats. During World War II, the United States designed an amphibious landing vehicle with a similar structure, although the functions of the two are completely different, but the basic structure of the two is highly similar, which can be regarded as a continuation of technology.