The purpose of Poison Gas warfare was to blind, iritate, blister, and/or asphyxiate the enemy. Poison Gas was first introduced by the French, despite common belief. The French used tear gases in the Battle of the Marne to distract the Germans, who were attempting a surprise attack on France by cutting through neutral Belgium. Due to its sucessful effects by iritating and causing the Germans to lose their battle, sending the Schlieffen plan to failure, the Germans took the time to perfect this new warfare of Poison Gas. Other forms of Posion Gas besides tear gases include Chlorine, Phosgene, and Mustard Gas. With these new gases, came more paranoia by the soldiers. Posion Gas changed warfare completely; because poison gas did not require an enemy to be present and soldiers felt they were never safe. They were extremely fearful of Poison Gases and its effects. Due to this fear, gas masks were created in order to protect soldiers from most cases of gas exposion.
Submarines (U-boats) have greatly impacted modern warfare. Supplies were more easily transported, and with transportation came the prevent of possivle transportation. Attacks/bombings on U-boats became a part of strategy in World War I.
Machine guns made it much simpler to aim and shoot targets at a more accurate and quicker speed. The mountability of this particular gun made it more popular for trench warfare in particular. Some machine guns are able to fire ammunition for hours at a time (with the trigger pulled down).
Tanks were very important during World War I, and were created in order to end the stalemate that went along with trench warfare. Tanks were armorous and for the most part protected the soldiers inside, whilst they drove towarss the enemy's trench, and fired at it