The war relied on the mass production of machine guns, artillery weapons, rifles, and ammunition, as well as on railways and steamships to transport weaponry and supplies to the front. Death and destruction occurred on an unimaginable scale. Around ten million soldiers, sailors, airmen, medical officers, and nurses died on the battlefields, in the trenches, in tunneling operations, in the air, at sea, and in the casualty clearing stations and military hospitals. Millions of civilians also died as a result of the war. Many were caught in the cross-fire and bombing. Others were driven from their homes, villages, and towns and died from infectious diseases, malnutrition, and starvation.
But the death toll didn’t end there. Over eight million horses died in the war. The opposing armies used them for transporting soldiers, ammunition, and guns. Some 7000 horses were killed during a single day of the Battle of Verdun in France, which lasted from February to December 1916. Tens of thousands of dogs were also killed in the war. They included dogs that hunted and killed rats in the trenches, messenger dogs, scout dogs that detected the scent of enemy troops, casualty dogs that found and carried medical supplies to wounded men on the battlefield, and guard dogs on sentry duty.
The Chemicals of War
The industrial-scale death and destruction during the war would not have been possible without the industrial-scale production of a vast variety of chemical substances, most importantly:
Explosives for shells, bombs, grenades, firearm ammunition, and mining operations;
Chemical warfare agents, commonly known as poison gases;
Metals and alloys for making weapons and ammunition.
The care of the sick and wounded and the protection of troops and sailors also relied on chemical materials:
Chemicals for gas masks;
Metals for making armour and steel helmets;
Dyes for military uniforms;
Light-sensitive chemicals for war photography and aerial reconnaissance;
Disinfectants to stop the spread of infections in the trenches;
Antiseptics for treating the wounded;
Anaesthetics for surgery;
Medicines, such as painkillers.
Chemists were needed to control the manufacture of “munitions, explosives, metals, leather, rubber, oil, gases, food, drugs,” noted British chemist Richard Pilcher in an article published in 1917. Pilcher was Registrar and Secretary of Britain’s Institute of Chemistry, of the forerunners of the Royal Society Chemistry. He called the war, “the chemists’ war.”
High Explosives and Propellants
Millions upon millions of artillery shells filled with high explosives were fired in the First World War. British 18-pounder guns, for example, fired 86 million shells in the war. The Germans bombarded the French with 100,000 shells in the first hour of their attack on the city of Verdun on 21 February 1916.
High explosives explode virtually instantaneously when detonated. The shock wave travels faster than the speed of sound. A wide variety of these explosives were used in the war, including picric acid, which has the formula C6H2(NO2)3OH. Its IUPAC name is 2,4,6-trinitrophenol. The British called the explosive “lyddite” after Lydd, a town in the south of England where it was manufactured. Trinitrotoluene (usually abbreviated to TNT), C6H2(NO2)3CH3, was employed extensively by all sides as a high explosive to fill shells. The compound was first prepared by a German chemist in 1863. Ammonal, an explosive mixture containing ammonium nitrate, NH4NO3, and aluminium, was used not only for filling shells, hand grenades, and trench mortar bombs, but also as a blasting explosive in tunneling operations. When TNT became scarce during the war, the British introduced the high explosive amatol, essentially a mixture of TNT and ammonium nitrate.
The opposing armies fired artillery shells using propellants contained in cartridges that were either loaded separately into the gun or attached to the base of the shell. Every round of ammunition for a machine gun, rifle, pistol, revolver, or any other type of firearm, contained a propellant. When the gun was fired, the propellant burnt extremely rapidly generating gases. The high pressure of the gases inside the firing chamber propelled the bullet at high velocity out of the gun barrel.
Propellants are low explosives. When ignited, their rate of explosion, that is the rate of the combustion process, occurs at less than the speed of sound, unlike high explosives.
Gunpowder, also known as black powder, was used for centuries as a propellant for firearms and cannons. The powder is a mixture of two chemical elements—carbon (in the form of charcoal) and sulfur—and one chemical compound: potassium nitrate. Combustion of the powder produces a lot of smoke.
During the Great War, the British gradually replaced gunpowder with cordite as a propellant for firearms and artillery weapons. Cordite contains two explosives—nitroglycerine (IUPAC name: 1,2,3-trinitroxypropane) and nitrocellulose—mixed together in petroleum jelly. It produced far less smoke than gunpowder when it burnt and was therefore known as a smokeless powder.
The Germans discharged chlorine gas against Allied troops at Langemarck, Belgium, on 22 April 1915, resulting in thousands of casualties. It was the first example in history of the use of a weapon of mass destruction. The British carried out its first chlorine gas assault against the Germans on 25 September 1915. Chemical warfare continued throughout the war.
Many of the so-called poison gases where not gases but liquids. For instance, mustard gas [(ClCH2CH2)2S, IUPAC name: bis(2-chloroethyl) sulfide], is an oily liquid that releases a toxic vapour with a smell of mustard oil. Various types of chemical warfare agents were used in the war. They included tear gases, also known as lachrymators, that were used to disable and disorient enemy troops by making them cry. The lachrymators used at the time were organic compounds containing a halogen such as bromine or iodine. Another type of poison gas, the choking agent, attacked the lungs when inhaled. These agents were lethal. Chlorine gas and phosgene (COCl2, IUPAC name: carbonyl dichloride) were widely used as choking agents by the Germans and the Allies. Blister agents, also known as vesicants, were the most notorious of all the chemical warfare agents. They attacked the whole body causing blisters and blindness and severe internal injuries if the vapour was inhaled. Mustard gas is a blister agent.
Most battlefield casualties during the war were caused by artillery shelling and rifle and machine gun fire. Chemical weapons accounted for less than five percent of all the casualties.
Chemical warfare in World War I can be divided into two components:
Offensive operations: firing chemical warfare agents from cylinders or in artillery shells, grenades, and bombs at the enemy;
Defensive measures, essentially protection against chemical warfare agents, typically using gas masks.
Early gas masks were primitive. In April 1915, Allied troops used handkerchiefs, rags, or socks soaked in water or urine to protect against chlorine gas. They were soon replaced by muslin envelopes containing cotton wool. Troops strapped the pads over their noses and mouths. They were dipped in aqueous solutions of washing soda (Na2CO3, sodium carbonate,) or baking soda (NaHCO3, sodium bicarbonate, IUPAC name: sodium hydrogen carbonate). These alkaline solutions neutralised chlorine, which is mildly acidic when dissolved in water.
Smoke hoods were developed later in the year. They consisted of flannel bags impregnated with chemicals that neutralised the poison gases. At the end of 1915, the Germans introduced snout-type canister gas masks. The canisters contained chemicals that adsorbed, destroyed or neutralised the toxic gases. The British box respirators, first used in February 1916, used similar chemicals to protect against poisonous gases. They included activated charcoal, a highly-porous form of carbon, to trap the gases.
Metals and Alloys
The manufacture of guns, shells, tanks, battleships, and other matériel relied extensively on the production of iron and steel. Iron and steel also played vital protective roles in the First World War. Tanks, famously used by the British at the Battle of Cambrai in November 1917, were protected from German bullets, shells, and grenades by armour that consisted of a tough flexible plate made from a nickel-containing alloy steel. A hard steel alloy containing nickel, chromium, and manganese was also widely used as armour by the German and British navies to protect their battleships.
Barbed wire made of steel protected trenches. Corrugated iron was employed to shore up the sides of trenches and as a roofing material. It was produced by dipping sheets of steel in a bath of molten zinc. The process, known as galvanisation, prevented rusting. Helmets, made of steel hardened with manganese, reduced the incidence of head injuries.
Many other metals and alloys were also used in the First World War, for example:
The frames of German airships known as zeppelins were made of an alloy containing aluminium;
Lead was used to make bullets;
Firearm and artillery cartridge cases were made of brass, an alloy of copper and zinc;
Foods, such as bully beef (corned beef) and jam, were distributed to troops in tin cans;
Platinum was used as a catalyst to speed up the chemical reactions that produced the nitric acid and sulfuric acid needed to make explosives such as TNT;
Mercury(II) fulminate, Hg(CNO)2, a highly explosive chemical used in firearm percussion caps, was made by the reaction of mercury with ethanol and nitric acid.
Every soldier, sailor, airman, medical officer, and nurse in the First World War wore a uniform of one sort or another. Some 43 million men in the Allied forces and 25 million men in the forces of the Central Powers fought in the war. That required the provision of at least 68 million military uniforms. British, American, and Russian soldiers wore khaki uniforms. Khaki and other drab colours, such as the field grey worn by the German army, provided camouflage and therefore helped to protect troops in the trenches from sniper fire.
Many of the dyes used to colour uniforms were synthetic organic dyes prepared from chemicals extracted from coal tar. Khaki-coloured fabrics were produced from cotton and woolen cloths or yarns dyed with mixtures of brown, yellow, and other organic dyes. Mixtures of mineral pigments such as iron- and chromium-containing salts were also used to produce khaki dyes.
The history of photography can be traced back to the early 1800s. By the beginning of World War I, photography had come of age. For the first time in European history, photographs and motion pictures provided dramatic scenes of the horrors of the war. The photographs were published in newspapers and magazines and the films shown in cinemas back home.
In addition, soldiers loved to pose in their uniforms for the camera and send postcards home. Photographs and film were also used for recruitment, training, official records, propaganda, and aerial reconnaissance.
Every unexposed photographic plate or film was coated with an emulsion of gelatine containing a light-sensitive silver halide salt such as silver bromide. The films were processed with solutions of chemical compounds, for example sodium thiosulfate (Na2S2O3), while still photographs were printed with inks composed of a range of chemical materials.
The Fight Against Infection
Troops in the First World War frequently lived for days in rat- and fly-infested trenches and dugouts where they were bitten by fleas and clothed in lice-ridden uniforms. The wounded sometimes had to lie on the battlefield for hours or days in filthy clothing, in mud and soil teeming with dangerously infectious micro-organisms. Inevitably, many fell prey to infectious diseases, for example:
Dysentery, a disease that caused acute diarrhoea, killed thousands in the war and was “one of the most fatal of foes to armies” according to one doctor. The disease was caused by bacteria in faeces and spread by food or water contaminated by faeces.
Typhoid, another bacterial infection, was also transmitted through food or water contaminated by urine or faeces. It was spread by “fingers and flies.”
Gas gangrene was caused by bacteria found in the soil. The disease produced gases inside the infected body tissue as the tissue decayed.
Typhus, an acute infectious fever, occurred in overcrowded and insanitary conditions. It was carried by lice. The disease killed 150,000 soldiers in Serbia during the first six months of the war.
A wide range of disinfectants and antiseptics were employed in the war to combat infection. Calcium hypochlorite, Ca(OCl)2, now commonly known as bleaching powder, was known as chloride of lime during the war. It was employed as a disinfectant in the trenches and used to sterilise drinking water and in antiseptic preparations for treating wounds. Carbolic acid, a coal tar chemical also known as phenol, was also used as a disinfectant and antiseptic. Mild disinfectant soaps, known as carbolic soaps, contained the acid. Many soldiers carried a first aid kit containing a phial of tincture of iodine, a weakly antiseptic solution that was applied to the skin to prevent wounds becoming infected. It was prepared by dissolving iodine in a solution of potassium iodide, ethanol, and water.
Eusol, which stands for Edinburgh University Solution of Lime, was a British antiseptic solution made by dissolving equal weights of chloride of lime and another antiseptic, boric acid, H3BO3, in water. Dakin’s solution was invented by British chemist Henry Dakin. The non-irritant antiseptic consisted of a dilute solution of household bleach, sodium hypochlorite, NaOCl, and boric acid. The solution did not store well and so had to be freshly prepared before treating wounds.
Medical officers and surgeons used a variety of naturally-occurring and synthetic chemicals as analgesics and anaesthetics to treat the sick and wounded in the First World War.
They included two of the fifty or more alkaloids that occur naturally in the opium poppy: morphine, a powerful painkiller, and codeine, a milder analgesic.
British army surgeons used chloroform (CHCl3, IUPAC name: trichloromethane), as a general anaesthetic to carry out amputations during the war. Inhalation of general anaesthetics such as chloroform induces temporary unconsciousness. Diethyl ether (C2H5OC2H5, IUPAC name: ethoxyethane) often known simply as “ether,” was also used as a general anaesthetic during the war. It was sometimes administered in combination with chloroform. Some surgeons preferred ethyl chloride (C2H5Cl, IUPAC name: chlorethane) or nitrous oxide (N2O, IUPAC name: dinitrogen monoxide) as anaesthetics, when available. Nitrous oxide, sometimes known as “laughing gas,” was also used in dentistry. It was prepared by gently heating ammonium nitrate.
Procaine (also known as novocaine, IUPAC name: 2-(diethylamino)ethyl 4-aminobenzoate), a synthetic organic chemical, was employed as a local anaesthetic in the war. Local anaesthetics kill pain in a region of the body without loss of consciousness. They were administered by injection.
The Dual Role of Chemicals
Chemical substances employed in the war not only resulted in death and destruction, but also protected and prolonged the lives of soldiers. Some chemicals were used for both purposes, for example:
Chlorine was used as a chemical weapon. The element was also a component of disinfectants such as bleaching powder and anaesthetics such as chloroform.
Picric acid was employed not only as a high explosive but also as an antiseptic to treat burns.
Phosphorus was used offensively as an incendiary material in shells and bombs and also defensively to generate smoke screens to conceal manoeuvres from the enemy.
Ammonium nitrate was a component of blasting explosives such as ammonal. It was also a fertiliser and used to generate the anaesthetic nitrous oxide.
About the article
Michael Freemantle < > is a science writer and a Fellow of the Royal Society of Chemistry. After a post-doctoral research fellowship at Oxford University (1967-1969), he worked in the chemical industry for two years. From 1971 to 1985, he taught chemistry at various levels both in the UK and abroad. In 1985, he joined IUPAC as Information Officer and editor of Chemistry International. From 1994 to 2007 he was European Science Editor/Senior Correspondent for Chemical & Engineering News, the weekly news magazine of the American Chemical Society. He was then appointed Science Writer in Residence, a part-time post, at Queen’s University Belfast and Queen’s University Ionic Liquid Laboratories for three years until 2010. He is the author, co-author, or editor of more than ten books on chemistry and related subjects. His three most recent books are:
The Chemists’ War: 1914-1918 (Royal Society of Chemistry, Cambridge, 2014);
Gas! GAS! Quick, boys! How Chemistry Changed the First World War (The History Press, Stroud, 2012);
An Introduction to Ionic Liquids (RSC Publishing, Cambridge, 2009).
Published Online: 2016-01-11
Published in Print: 2016-01-01