World War I weapons included types standardised and improved over the preceding period, together with some newly developed types using innovative technology and a number of improvised weapons used in trench warfare. Military technology of the time included important innovations in grenades, poison gas, and artillery, along with essentially new weapons such as the submarine, warplane and tank.
Infantry weapons for major powers were mainly bolt action rifles, capable of firing ten or more rounds per minute. German soldiers carried 7.92 Mauser rifles, which were good for penetration. The British carried the famous Lee–Enfield rifle. Rifles with telescopic sights were used by snipers, and were first used by the Germans.
Machine guns were also used by large powers; a favorite was the Maxim gun, a fully automatic weapon, with a high volume of concentrated fire, and its French counterpart, the Hotchkiss M1914 machine gun. Their use in defense, combined with barbed wire obstacles, converted the expected mobile battlefield to a static one. The machine gun was useful in stationary battle but was not practical for easy movement through battlefields, and was therefore often dragged or disarmed and carried.
Grenades proved to be effective weapons in the trenches but when the forces arrived their numbers and capabilities were inadequate[clarification needed]. Hand grenades were used and improved throughout the war. Contact fuzes became less common, replaced by time fuzes.
The British entered the war with the long-handled impact detonating "Grenade, Hand No 1". The No. 15 "Ball Grenade" partially overcame its inadequacies. British forces however mainly used an improvised hand explosive that was at times more difficult to use, yet still useful in battle. This was the Double Cylinder "jam tin" which consisted of a tin filled with dynamite or guncotton, packed round with scrap metal or stones. To ignite, at the top of the tin there was a Bickford safety fuse connecting the detonator, which was lit by either a cigar, or a second person. The "Mills bomb" (Grenade, Hand No. 5") was invented during the war and came into use in 1915. Its improved fusing system killed more of the enemy and fewer of its users. The French meanwhile introduced the F1 defensive grenade.
The major grenades used in the beginning by the German Army were the impact-detonating "discus" or "oyster shell" bomb and the Mod 1913 black powder kugelhandgranate with a friction-ignited time fuse. During the war Germany developed the much more effective Model 24 grenade or "potato masher" whose variants remained in use for decades.
Hand grenades were not the only attempt at projectile explosives for infantry. A rifle grenade was brought into the trenches to attack the enemy from a greater distance. The Hales rifle grenade got little attention from the British Army before the war began but, during the war, Germany showed great interest in this weapon. The resulting casualties for the Allies caused Britain to search for a new defense.
The Stokes mortar, a lightweight and very portable trench mortar with short tube and capable of indirect fire, was rapidly developed and widely imitated. Mechanical bomb throwers of lesser range were used in a similar fashion to fire upon the enemy from a safe distance within the trench.
The British and German armies had already changed from red coat (British army) (1902) or Prussian blue (1910) for field uniforms, to less conspicuous khaki or field gray. Adolphe Messimy, Joseph Gallieni and other French leaders had proposed following suit, but the French army marched to war in their traditional red trousers, and only began receiving the new "horizon blue" ones in 1915.
A type of raincoat for British officers, introduced long before the war, gained fame as the trench coat.
The principal armies entered the war with mainly cloth caps or leather helmets. They hastened to develop new steel helmets, in designs that became icons of their respective countries.
Chemical weapons were first used systematically in this war. Chemical weapons in World War I included phosgene, tear gas, chlorarsines and mustard gas. A secret report by Lt Colonel C. G. Douglas, on the physiological effects of chemical weapons, stated that "the particular value of the poison [mustard gas] is to be found in its remarkable casualty producing power as opposed to its killing power". The report said that only 1% of British troops died due to chemical weapons, while an estimated 181,000 soldiers were hospitalized due to them. Chlorine gas was first used by Germany, in the Second Battle of Ypres in 1915, with great effect.
Chemical weapons were easily attained, and cheap. Gas was especially effective against troops in trenches and bunkers that protected them from other weapons. Studies show that over 1,300,000 people were exposed and intoxicated by gas during the First World War, and 90,000 were killed due to gasses.
Chemical weapons attacked an individual’s respiratory system. The concept of choking easily caused fear in soldiers and the resulting terror affected them psychologically. Because there was such a great fear of chemical weapons amongst the soldiers it wasn’t uncommon that a soldier would panic and misinterpret symptoms of the common cold as being affected by a poisonous gas.
Aviation in World War I started with primitive aircraft, primitively used. Technological progress was swift, leading to ground attack, tactical bombing, and highly publicized, deadly dogfights among aircraft equipped with forward-firing, synchronized machine guns from July 1915 onwards. However, these uses made a lesser impact on the war than more mundane roles in intelligence, sea patrol and especially artillery spotting. Antiaircraft warfare also had its beginnings in this war.
German strategic bombing during World War I struck Warsaw, Paris, London and other cities. With the small loads carried by Zeppelins and the first, primitive bombers developed specifically for the purpose, direct damage was slight. Large efforts, however, were diverted from more fruitful military activities to the defense of cities. The Allies made much smaller efforts in bombing the Central Powers.
In the 19th century, Britain and France exploited the rapid technical developments in artillery to serve a War of Movement. Such weapons served well in the colonial wars of that century, and served Germany very well in the Franco-Prussian War, but trench warfare was more like a siege, and called for siege guns. The German army had already anticipated that a European war might require heavier artillery, hence had a more appropriate mix of sizes. Foundries responded to the actual situation with more heavy products and fewer highly mobile pieces. Germany developed the Paris guns of stupendous size and range. However, the necessarily stupendous muzzle velocity wore out a gun barrel after a few shots requiring a return to the factory for relining, so these weapons served more to frighten and anger urban people than to kill them or devastate their cities.
Field artillery entered the war with the idea that each gun should be accompanied by hundreds of shells, and armories ought to have about a thousand on hand for resupply. This proved utterly inadequate when it became commonplace for a gun to sit in one place and fire a hundred shells or more per day for weeks or months on end. To meet the resulting Shell Crisis of 1915, factories were hastily converted from other purposes to make more ammunition. Railways to the front were expanded or built, leaving the question of the last mile. Horses in World War I were the main answer, and their high death rate seriously weakened the Central Powers late in the war. In many places the newly invented trench railways helped. The new motor trucks as yet lacked pneumatic tires, versatile suspension, and other improvements that in later decades would allow them to perform well.
The British Royal Navy and French industrialists invented tanks in World War I. After initial small-scale use they brought success in the opening assault of the Battle of Cambrai (1917) until German artillerymen learned to resist them. Despite rapidly increasing French production, their numbers remained too small to make more than a modest impact on the progress of the war in 1918. Germany used a few captured enemy tanks, and made a few. Plan 1919 outlined the future use of massive tank formations in great offensives combined with ground attack aircraft.
E. Jones, B. Everitt, S. Ironside, I. Palmer and S. Wessely (2008). Psychological effects of chemical weapons: a follow-up study of First World War veterans. Psychological Medicine, 38, pp 1419–1426. doi:10.1017/S003329170800278X.