During WW2, all the major countries involved used submarines.
U-boats
See website: Submarine
Germany
the submarine played a key part in world war 2 for many countries, Germany used them extensively against British shipping and to destroy royal navy ships, the British used them again to destroy a few well known German ships, Japan had submarines as well like the midget submarine they also used to attack the US, ad the united states also had submarines in the pacific theater.
USSR
A U-boat was a submarine used by Germany in World War 1 and World War 2.
The first documented use of sonar was during World War I by the British Royal Navy to detect submarines. The technology was further developed during World War II for anti-submarine warfare.
Asdic
H. L. Hunley was the name of the Confederate submarine that was used during the American Civil War. It was the first combat submarine to successfully sink an enemy ship.
professor Robet Mc-Darblingberg came up with the idea(in WWI) that the Germans need to perfect and inovate the sub-marine into a killing machine. The sub-marine was used to destroy enemy merchant ships as well as military ships and reeked hacoc on the seas in WWI.
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