Allied cargo ships were the Germans primary targets.
Oilers then merchantmen.
Near South American oil fields.
Yes, German submarines were very effective in both world wars. The Germans built excellent submarines and still do.
Atlantic Ocean.
Wolfpack
German submarines were referred to as U-boats during the world wars.
The submarines were either called "submarines" or "U-boats." The German submarine was called the "U-boat"
Underseaboats.U-boats
759
The name U-boat was applied to German submarines.
Submarines, commerce raiding.
U-boats. (German submarines)