Germany changed the tactic during WWI via unrestricted submarine warfare, which meant that German U-boats could attack without warning any vessel it came across.

The wreck of a WWI German U-boat sunk by the U.S. Navy in 1922 has been discovered off the East Coast of the United States, about 40 miles off Virginia and at a depth of about 400 feet.

Revealing a WWI drama: How modern technology is shedding new light on the horrors of submarine warfare Exclusive: Archaeologists explore a German U-boat for the first time since it sunk 103 years ago ...

The wreck of a World War I German submarine has been discovered off the coast of Scotland by marine engineers surveying the route of an undersea power cable.

A century-old German U-boat was discovered in sonar scans by wind farm developers.

Both submarines were used by the Imperial German Navy, which controlled the waters off the Belgian coast during WWI. One of the submarines is a type "U-5" U-boat measuring around 187 feet in ...

BRUSSELS, Belgium — The well-preserved wreck of a German submarine sunk during World War I has been found in the North Sea and may have the bodies of its crew still on board, Belgian officials ...

The wreck of the German U-Boat U-111 was intentionally sunk by the U.S. Navy in 1923 after it was captured at the end of the war.

Revealing a WWI drama: How modern technology is shedding new light on the horrors of submarine warfare Exclusive: Archaeologists explore a German U-boat for the first time since it sunk 103 years ago ...

Submarines came to the forefront of military navies with the advent of WWI, as Germany's dangerous U-boats proved a formidable force throughout the conflict.