The purpose of poison gas was to stop the soldiers before they got any further on the ground. It was used in the trenches even when there was no fighting going on. It changed modern warfare because the person didn't have to be there to kill an enemy. The poison gas could go off at anytime and kill an enemy.
The purpose of the machine gun was to fire as many bullets at the enemy as possible. The machine gun could shot hundreds of bullets and could slaughter a whole front line in no time. This changed modern wwarfare because now enemies can't run at each other and shoot, they have to have cover. This also changed the number of deaths since it could kill so many people at a time. The machine gun is so much more accurate than the previous guns that it would always hit its target.
The purpose of the tank was that it was place where you would be safer than in the trenches and could also shoot at people. It could go in the trenches and could move people around safely. The tank changed warfare because it allowed people to have small vehicle to be transported in and as well shoot at people. This was able to change the way that wars are fought on the ground.
The purpose of submarine was to take down navy ships in sea battles. It was a new easy way to win naval battles out in the middle of the ocean because the ships couldn't really know if it was coming. This changed modern warfare because it was an easy to take down naval ships without losing any of your own people. This weapon has changed naval battles for the rest of the world.
"Poison Gas and World War One." Poison Gas and World War One. Web. 15 Jan. 2015.
"Unrestricted Submarine Warfare." Unrestricted Submarine Warfare. Web. 15 Jan. 2015.