Underseaboats.
They're german submarines, used in world war 1 and world war 2
Destroyers, aircraft, and the convoy system.
During WW1, German U-boats (submarines) used torpedoes to sink boats and ships belonging to the Allies or any vessel aiding the Allies war cause.
Britain, France, Germany, Italy and USA all used submarines during WW1
machine guns tanks poison gas submarines airplanes
The Allies, including Great Britain, USA, Russia and Italy all had submarines during WW1. In general they were not nearly as advanced or successful as the German U-boats.
They were the submarines of the German Navy. U-boat is short for undertseeboote (undersea boat).
Submarines.
Britain, USA, Germany and Italy used submarines during WW1
yes
Submarines fought in both WW1 and WW2.
Do you mean the observation balloons? These were called Drakens.also - zeppelins were used for observation at first.