The USS Tang was on it's fifth war patrol in the China Sea. When it came upon a convoy of merchant ships the last was fired and it circled. USS Tang was hit just after the coning tower near the engine rooms. It sunk is shallow water.
it sunk by a torpedo from U-20, a submarine
This is an old and a common term. The torpedo has been used since the first submarine's were used in war time.
Mk14 torpedoes and the Torpedo Data Computer (TDC)
It's kind of a missile that runs in water. It's got a warhead, an engine, a means of propulsion and a tank of fuel. Since the 20th century that is essentially correct. Earlier a Torpedo was What today would be called a mine. IN the civil war the submarine CSS Hunely had a torpedo on a long pole. Earlier , in 1776, the the Submarine Turtle used a Spar Torpedo in the revolutionary war. Today. A torpedo is most likely to be a self guiding, electrically driven weapon that could be compared to an underwater missile.
It was the RMS Falaba, that went down with 104 people on 28 March, 1915. It was the first passenger ship sunk by torpedo during World War I.
The deadliest torpedo of WWII was the oxygen fuelled Japanese Long Lance torpedo.
Germany
A U-boat was a submarine used by Germany in World War 1 and World War 2.
United States Submarine Operations in World War II was created in 1949.
The most famous of all of the German boats in WW2 was the U-boat, it was a kind of submarine that fired torpedo's and a ship before it could see it or even know that an enemy was nearby.
The submarine.
United States Submarine Operations in World War II has 577 pages.