The US helped France in world war 1 with submarines in the Atlantic.
Sonar was used widely in World War II in an effort to locate enemy submarines. It wasn't as sophisticated as it is today, but it did help. Actual numbers are difficult to come by, but sonar was effective in the successful attacks on several submarines.
Why don't you just Google "World War 1 Submarines?"
Yes, German submarines were very effective in both world wars. The Germans built excellent submarines and still do.
World War I submarines were primarily used to locate and attack surface cargo and warships.
Submarines were sometimes referred to as submersibles.
The submarines were either called "submarines" or "U-boats." The German submarine was called the "U-boat"
They did not in any way.
this is where they got help
Shallow diving submarines are used for reef watching in many parts of the world.
2,200,000 Soldiers 97 Warships 40 Submarines.
Submarines changed war. They played a big part of World War I and II.