Machine Gun : Machine guns played a significant role in WWI because it showed death with 38 million military and civilians. It was created 30 years before WWI in 1884 by Hiram Maxim. It wasn't much used in WWI but similar designs of the "Maxi Gun" were used in battle. The machine gun allowed soldiers to shoot around 400-600 rounds per minute. The machine guns were very heavy so it would need 3-5 people in order to move it or operate it. The gun would also over heat and get jammed easily with repeated use which would result it into not working at all.
Tank : Tanks played a significant part in WWI because as trench warfare was being used it was becoming difficult to travel across the fields of battle. It was revealed in 1915 on September 6, however it was very weak so it wasn't used in combat until a year later when they made a stronger version. One tank commander wrote: "I and my crew did not have a tank of our own the whole time we were in England. Ours went wrong the day it arrived. We had no reconnaissance or map reading….no practices or lectures on the compass….we had no signaling….and no practice in considering orders. We had no knowledge of where to look for information that would be necessary for us as tank commanders, nor did we know what information we should be likely to require.”
Poison Gas : Poisonous gas was important in WWI as it was Germany's only use of defense on April 22, 1915 during the Second Battle of Ypres. John French who is the commander in chief of the British Expeditionary Force also known as BEF wrote: “All the scientific resources of Germany have apparently been brought into play to produce a gas of so virulent and poisonous a nature that any human being brought into contact with it is first paralyzed and then meets with a lingering and agonizing death.”
Tracer Bullets : When it would be night time during the war it would be difficult for soldiers to see if they hit their target or not. The bullet was invented so it could help, and was invented by Great Britain. Bright flaming paths would be there so that whoever was shot by the bullet the soldiers could find them. The disadvantage would be that whoever was firing the bullet they would know where that person is as well.
Depth Charges : Depth Charges played a significant role in WWI because it was used ships to attack submarines. It was developed by Great Britain to attack the German submarines, it was a canister filled with explosives and it was rolled off or dropped of the stern of the boat where they would think the submarine is at. The explosive when dropped in the water would rarely explode close enough in order to sink the submarine. If it weren't to explode the submarine it would loosen the joints and damage the submarines instruments which would make it go to the surface then it would be finished by a naval gunfire.