Many weapons, such as the machine gun, submarine and bolt-action rifle, first saw major use in World War I. Many other contemporary inventions, such as the airplane, were first adapted to military purposes for what was then known as the Great War. In addition, there were many weapons which were invented and first saw use during the course of the war, which was fought between 1914 and 1918.

Flame Throwers

The German army began experimenting with flame throwers as early as 1900 and stationary versions of the new weapon were issued to select German units in 1911. Deployed by German troops on the Western Front in 1914, flame throwers were first used extensively during the Battle of Hooge, fought in Flanders, Belgium on July 30, 1915. During the battle, German troops used newly-developed portable flame throwers to dislodge Allied troops from entrenched positions. Flame throwers were mainly used to clear front line trenches. They had limited range of approximately 100 feet and required a two-man crew to operate. British and French forces experimented with flame throwers, but never used them as extensively as the Germans did.

Submachine Guns

The Germans first introduced the MP18 Bergmann Muskete submachine gun – called a "machine pistol" – in 1918, in the closing months of World War I. The light-weight weapon had a rapid rate of fire and was easy to use in trenches and other confined spaces. The MP18 fired standard 9mm rounds at a rate of 400 rounds per minute and featured a barrel slightly under eight inches long. Submachine guns were introduced too late in the war to have a major impact, but would see significant use by all major combatants in World War II.

Chemical Weapons

Modern chemical weapons including mustard gas were first used by the German army during World War I. The German army first attempted to use the new weapons at Neuve Chapelle, France in October 1914, but the artillery shells carrying the gas missed their targets. They later used chemical weapons against Russian forces on the Eastern Front in January, 1915. Most of the poison gas froze, but the Russian army sustained more than 1,000 deaths. The first major use of chemical weapons was at the Second Battle of Ypres on April 22, 1915 in Belgium. Germans used wind-bourne chlorine gas against French and Algerian forces, crippling two divisions.

Continued Use of Chemical Weapons

Britain, France and the United States – which was not yet in the war – rapidly developed their own chemical weapons and both sides developed defenses against the weapons. Future U.S. President Harry S. Truman served in an artillery unit that used poison gas against German troops. Around 500,000 soldiers were injured by chemical weapons during World War I. Nearly 30,000 died. The further use of chemical weapons was banned by the Geneva Conventions of 1925.

Tanks

The tank was conceived by British Col. Ernest Swinton and Secretary of the Committee for Imperial Defense William Hankey as a way of transporting troops and weaponry across "no man's land," the heavily fortified area between trenches. The first tank was produced in England in September, 1915. The first major use of tanks – by the British – was in the First Battle of the Somme on September 15, 1915. The tanks failed to break the battle's deadlock, but the Allied commander, British Gen. Sir Douglass Haig, recognized their potential and ordered more delivered to the front. Other forces on both sides of the war quickly developed their own versions of the tank. The tank got its name because English metal workers were told the new machine was to be used to deliver water on the battlefield.