1775, the North American War of Independence finally broke out. Under the leadership of Commander-in-Chief Washington, the American people took up arms one after another and launched a life-and-death battle with the British army, driving the British army from the mainland to the sea. The whole country celebrated this decisive victory. How can we tolerate the glory of other countries in destroying Britain and then organize the defeated troops to make a comeback? Although the British colonial rulers lost their land superiority, their maritime superiority still existed. They assembled a large number of warships and bombed the US coastal defense forces in turn, causing heavy casualties and greatly weakening the momentum of the US military. The British army became more and more rampant when it saw that the American army had neither the potential to parry nor the strength to fight back. Warships are on the rampage along the coast, throwing their weight around. He fired several shots at the coastal defenders from time to time, and then swaggered away triumphantly. Faced with the provocation and bullying of the British army, the American soldiers gnashed their teeth with anger: "This is simply riding on someone's neck to shit! If I can sneak past and sink some of its ships, I should feel even more revenge! "
One of the soldiers, David bushnell, didn't swear, but kept his mouth shut and said nothing. He thinks it's no use shouting. We should work out a way to deal with enemy ships as soon as possible. Bushnell has been thinking hard about how he can bypass their boat at once. From the air? No, it is easy to expose the target; From underwater? No, who can resist swimming for so long? Besides, there is not enough strength! What should I do? "He's knocking.
One night, after he and several soldiers were fired, he went for a walk by the sea. They climbed to the rocks; While chatting, enjoy the sea view in the sunset. I have seen enough of the distant view and close view, the water is clear and the aquatic life is vivid. They saw a group of lively small fish swimming freely in the water, as if they were foraging for food and playing. Suddenly, a big fish swam quietly under the water, swam under the small fish, jumped up suddenly and bit a small fish. The other little fish were so scared that they parted ways. The soldiers saw this "naval battle" in the underwater world and found it very interesting. Bushnell was greatly inspired by this: this is how the clumsy big fish caught the clever and quick small fish. Can you build a ship like a big fish, and dive into the bottom of a British warship in the latent water unnoticed, and lay a mine to blow it up and sink it? If you can do it, how happy it will be! The more he thought about it, the more fascinated he became. He didn't sit there until his companion told him to go. "Ah! What's the matter with you? I miss your lover, hehe! " His companion slapped him.
"I have an idea, I can sink!" Bushnell's words puzzled his companions. So he elaborated his thoughts. Hearing this, the companions all thought it was a good idea. Suddenly someone asked, "Fish can float and sink freely in the water, but a boat is different. It's easy to float on the water, but can you dive? " Bushnell was asked to remain silent. Yes, how can I make the boat float and sink? Why can fish do this? He patted his thigh: "I have! This kind of fish floats to the surface for a while and dives to the bottom for a while, relying on the swim bladder in its belly. If we also forge a' prostitute' for the ship, won't the problem be solved? "
Bushnell led his companions to build a secret ship that can sneak underwater. I wanted to make it look like a fish, but it looked like a turtle. Therefore, the companions gave it a code name-tortoise. This secret spaceship, code-named "Turtle", has a water tank similar to a swim bladder at the bottom, and there are two pumps in the water tank. When the ship sinks on the water, it will fill the water tank with water. When the ship is going to float underwater, it will drain the water in the cabin and press the air into the water tank. Imitating the fin of a fish, two propellers were installed outside the turtle: one for forward and backward, and the other for upward and downward. In addition, the turtle has a rudder at the tail, which can control the course.
One night, bushnell, with a few soldiers, drove the "turtle" quietly close to the British warship, then dived into the water and dived under the British warship. They want to use the drill pipe at the top of the turtle to drill through the enemy ship and then release the mine. Unexpectedly, the bottom of the British ship was covered with a thick layer of metal and could not be drilled in for more than an hour. The soldiers couldn't hold their breath down there, so they had to come up for air. At this time, the night is deep and dark, and the water and sky are the same, and I can't tell the direction at all. The British army found the "turtle" and started warships to pursue it. The "turtle" was scared to retreat again and again, but it could not get up quickly, and it was about to be hit by an enemy ship. At this extremely critical moment, bushnell used his quick wits to untie the spare mine, lit the fuse, and hurried into the "Turtle", which dived into the water. The British ship is looking for the whereabouts of the monster. Suddenly, there was a loud noise beside the ship and the warship caught fire. The British army turned around and fled while fighting the fire, for fear that the monster would quietly follow. Since then, British ships have never dared to show off near the American coast.
Later, after people's continuous improvement, they made a new mysterious weapon-submarine. The submarine showed great power in the naval battle. In World War II, only German submarines sank 782 transport ships of the Anglo-American Atlantic Fleet, which caused great damage to the other side's transport lines.
At present, submarines are mainly used for developing marine resources and scientific investigation in addition to combat. Its role has also changed from destruction and interference to benefiting mankind.