Poisonous gases were known about for a long time before the First World War but military officers were reluctant to use them as they considered it to be a uncivilized weapon. The French Army were the first to employ it as a weapon when in the first month of the war they fired tear-gas grenades at the Germans.
In October 1914 the German Army began firing shrapnel shells in which the steel balls had been treated with a chemical irritant. The Germans first used chlorine gas cylinders in April 1915 when it was employed against the French Army at Ypres. Chlorine gas destroyed the respiratory organs of its victims and this led to a slow death by asphyxiation.
General William Robertson recommended Brigadier General Charles Howard Foulkes to General John French as the best man to organise the retaliation. Foulkes accepted the post he eventually received the title of General Officer Commanding the Special Brigade responsible for Chemical Warfare and Director of Gas Services. He worked closely with scientists working at the governmental laboratories at Porton Down near Salisbury. His biographer, John Bourne, has argued: "Despite Foulkes' energy, the ingenuity of his men and the consumption of expensive resources, gas was ultimately disappointing as a weapon, despite its terrifying reputation."
It was important to have the right weather conditions before a gas attack could be made. When the British Army launched a gas attack on 25th September in 1915, the wind blew it back into the faces of the advancing troops. This problem was solved in 1916 when gas shells were produced for use with heavy artillery. This increased the army's range of attack and helped to protect their own troops when weather conditions were not completely ideal.
After the first German chlorine gas attacks, Allied troops were supplied with masks of cotton pads that had been soaked in urine. It was found that the ammonia in the pad neutralized the poison. Other soldiers preferred to use handkerchiefs, a sock, a flannel body-belt, dampened with a solution of bicarbonate of soda, and tied across the mouth and nose until the gas passed over. It was not until July 1915 that soldiers were given efficient gas masks and anti-asphyxiation respirators.
One disadvantage for the side that launched chlorine gas attacks was that it made the victim cough and therefore limited his intake of the poison. Both sides found that phosgene was more effective poison to use. Only a small amount was needed to make it impossible for the soldier to keep fighting. It also killed its victim within 48 hours of the attack. Advancing armies also used a mixture of chlorine and phosgene called 'white star'.
Mustard Gas (Yperite) was first used by the German Army in September 1917. The most lethal of all the poisonous chemicals used during the war, it was almost odourless and took twelve hours to take effect. Yperite was so powerful that only small amounts had to be added to high explosive shells to be effective. Once in the soil, mustard gas remained active for several weeks. The Germans also used bromine and chloropicrin.
In July 1917, David Lloyd George appointed Winston Churchill as Minister of Munitions and for the rest of the war, he was in charge of the production of tanks, aeroplanes, guns and shells. Clive Ponting, the author of Churchill (1994) has argued: "The technology in which Churchill placed greatest faith though was chemical warfare, which had first been used by the Germans in 1915. It was at this time that Churchill developed what was to prove a life-long enthusiasm for the widespread use of this form of warfare."