Yes, before cruise missiles came about, submarines were armed solely with torpedoes and, more common in WW2, deck guns.
During WW 1, submarines played a major part of a major war for the first time. The role of a submarine was basically to use torpedoes to sink enemy warships and cargo vessels.
Torpedoes were the main weapon. The submarines also had a naval gun that they would use on unarmed ships and many had machine gun mounts as well.
Submarines used torpedoes in anti-shipping roles hoping to cripple the enemies ability to supply and reinforce points of conflict as well as to hamper the enemies economy .
Why don't you just Google "World War 1 Submarines?"
Submarines were sometimes referred to as submersibles.
1, 200,000 Soldiers 30 Warships 11 Submarines.
Steel plates.
Atlantic Ocean.
2,200,000 Soldiers 97 Warships 40 Submarines.
Yes, German submarines were very effective in both world wars. The Germans built excellent submarines and still do.
The US helped France in world war 1 with submarines in the Atlantic.
In the World War One era, it was vital for cargo ships to cross the Atlantic Ocean for the transport of supplies from the USA to Western Europe. The major danger in this was that German submarines were able to use torpedoes to sink ships, both military and merchant vessels. The ship sailing formation called a convoy was designed to protect ships in the convoy and to destroy German submarines.