1915: April 22
In what would turn out to be the only major German offensive on the Western Front in 1915, Allied troops were left in shock when 150 tons of lethal chlorine was fired along the frontline at Ypres.
On April 22 a bombardment of the Allied line began. But, instead of the expected follow-up attack by ground troops, the Allied soldiers were thrown into panic when a mist of greenish-yellow chlorine gas rolled towards them.
10,000 soldiers of French Algerian and territorial divisions were affected on the frontline. Half died within ten minutes and those who survived were temporarily blinded, coughing heavily. Around 2,000 of these troops were taken as prisoners of war.
The success of the gas attack surprised even the Germans who had not expected to be able to make any real breakthrough at Ypres. Chemical warfare had entered the military vocabulary.