Mustard gas was used during World War I to poison and kill soldiers without needing to fire at them. It was also used for tactical purposes such as flushing soldiers out of trenches. This was first used by the German soldiers.
Machine guns were used by all of the nations mainly as a defensive strategy. These guns required a team of four to six people to operate. They would overheat and needed to be cooled either by liquid or by air. They supposely supposed to shoot four hundred to six hundred small calibre bullets per minute. The machine guns brought major casualties on all nations.
The tank was first introduced during Word War I. But the first models were considered extremely slow and unreliable. During the time, it would not work if the terrain was not flat. There would be at least ten people needed to operate the device. Many times, the tanks would sink into the trenches and be stuck. They were affective however, once stationary with its machine guns and guns attached to it.
Submarines were fist used during World War I used to scout and entrap other navy ships. There was a small amount of submarines produced on all sides. They were equipped with torpedoes and various wraps capable of taking down other ships.
"Spartacus Educational." Spartacus Educational. Web. 13 Jan. 2015. <http://spartacus-educational.com/FWWmustard.htm>.
"Firstworldwar.com." First World War.com. Web. 13 Jan. 2015. <http://www.firstworldwar.com/weaponry/machineguns.htm>.
"Tanks and World War One." Tanks and World War One. Web. 13 Jan. 2015. <http://www.historylearningsite.co.uk/tanks_and_world_war_one.htm>.