Tank, machine gun, submarine, poison gas
A tank is used to cross many different types of land. it was first used in the Battle of the Somme in 1916.
The machine gun fires bullets automatically and more frequently than most guns. Machine guns wipe out many attacks at once making it difficult for forces to advance.
In 1914 the Germans introduced the submarine using its primary weapon against ships, the torpedo, an underwater missile.
Poison gas was used to protect trenches and could be prevented from inhaling by wearing a mask. Some gases caused blindness, death by choking, or servers blisters.