Tanks were first brought into World War I by the British. The tank's design gave it multiple advantags because it allowed it to maneuver over different types of terrain as well as trenches. The tank used caterpillar tracks to help it move acoss mud. The tank was not affected by small firearms because of the outter shell, in addition to the tough shell, it carried two machine guns on it.
Machine guns were first invented by Hiram Maxium for the British. However, the British orginially rejected the weapon and the Germans quickly turned the invention around into one of their own called the Maschinengewehr 08. The first machine guns were held up on a tripod and they had to be operated by 4-6 soldiers. The guns would get overheated very quickly and it would require a lot of water to cool them off. When they were working properly, the gun could fire 400-600 bullets a minute, giving it the potential to wipe out a front line in a matter of seconds.
Poison gas was first used by the German Army in late 1914. They first used tear gas but it eventually evolved into chlorine gas. When someone inhaled chlorine, their respiratory system would die and they would sufficate. After chlorine gas came phosgene. Phosgene would cause a person to violently choke and cough; it was proved to be more fatal. Mustard gas was the last deadly gas used in World War I. Mustard gas would cause severe interior and exterior burns. Poison gas would be put into shells and hurled into enemy trenches. Once the gas took effect, the soldiers who hurled the shells would wait until the gas cleared to take over the trench.
Submarines were first invented by the Germans and they were called U-boats. U-boats were very effective in sinking British supply ships. By the end of the war, German U-boats sank about eleven million pounds of Allied supplies. Germany saw the efficiency of U-boats and started to mass produce them; they started the war with 29 and at the end they had about 360. However, 178 of the 360 U-boats ended up being destroyed in the war.