They were called U-Boats. These boats were first used by Germany when they tried to blockade British ports. However, Britain fought back, and was able to push Germany back towards their ports and blockaded the German ports.
Later, Germany used these boats to attack any ship that entered the part of the sea they were grading. After sinking the Lusitania (a British passenger ship caring Americans, workers, and traveler) President Wilson demanded that Germany stop sinking any ship that entered into what Germany thought was 'there territory'. After signing a pledge with The United States Germany promised not to sink any more passenger ship boats without giving them a warning before they can attack.
* Later however Germany will not abide by this pledge, and this will be one of many push factors for the United States entering WWI.
Why don't you just Google "World War 1 Submarines?"
World War I submarines were primarily used to locate and attack surface cargo and warships.
Submarines changed war. They played a big part of World War I and II.
Yes
Submarines were sometimes referred to as submersibles.
Yes, German submarines were very effective in both world wars. The Germans built excellent submarines and still do.
2,200,000 Soldiers 97 Warships 40 Submarines.
The US helped France in world war 1 with submarines in the Atlantic.
Steel plates.
326
Atlantic Ocean.
Wolfpack