Gas attack
On 22nd April 1915, during the early stages of the Second Battle of Second Battle of Ypres, the German Army carried out the first large-scale, deliberate gas attack in modern warfare. This marked a turning point in the conduct of the First World War, introducing chemical weapons as a terrifying new method of fighting.
The architect behind the attack was the German High Command, with significant influence from the chemist Fritz Haber, who had strongly advocated for the use of poison gas as a means to break the stalemate of trench warfare. Haber personally oversaw aspects of the operation and believed gas could create a decisive breakthrough if deployed under the right conditions.
The Germans chose a sector of the front near the Belgian town of Ypres, where Allied lines were held primarily by French colonial troops. Opposite them, the German Fourth Army, commanded by Albrecht, Duke of Württemberg, prepared a massive release of chlorine gas. Over several weeks, German engineers had installed thousands of gas cylinders along a roughly 6-kilometre stretch of front line, carefully concealing them within their trenches.
In total, around 150 tons of chlorine gas were prepared for release. Unlike later gas attacks that used artillery shells, this first major deployment relied on the controlled release of gas from cylinders. The success of the plan depended heavily on weather conditions. On the late afternoon of 22 April, a steady northeasterly breeze began to blow toward the Allied lines, providing the opportunity the Germans had been waiting for.
At approximately 5:00 p.m., German troops opened the valves on the cylinders. A dense, greenish-yellow cloud of chlorine gas drifted slowly across no man’s land toward the unsuspecting Allied trenches. At first, many soldiers did not understand what they were seeing. Some believed it to be smoke from a fire or a new type of artillery barrage.
As the gas reached the front lines, its effects were immediate and devastating. Chlorine reacts with moisture in the lungs to form hydrochloric acid, effectively burning the respiratory system from within. Soldiers began coughing violently, choking, and gasping for air. Eyes burned intensely, and many were blinded. Panic spread rapidly as men tried to flee the invisible, suffocating threat.
The troops who bore the brunt of the attack were primarily French colonial units, including divisions of Algerian Tirailleurs and Zouaves. These soldiers, positioned in the forward trenches, had no protective equipment and no prior warning of such a weapon. Within minutes, large sections of the line collapsed as men died or fled in terror.
The gas created a gap approximately 6 kilometres wide in the Allied front. Thousands of soldiers were incapacitated almost immediately. It is estimated that around 6,000 men were killed outright or died shortly after exposure during the initial release, with many more wounded. Survivors often suffered long-term lung damage, leaving them vulnerable to infection and chronic illness.
Despite the scale of the devastation, the German forces were initially unprepared to fully exploit the breakthrough. Many German troops themselves were wary of advancing into areas still contaminated by gas, and they lacked sufficient reserves to push forward decisively. This hesitation allowed Allied forces, including Canadian troops arriving in support, to stabilize the line and prevent a complete collapse.
The psychological impact of the attack was immense. For the first time, soldiers faced a weapon that could silently drift across the battlefield, bypassing traditional defenses and inflicting agonizing deaths. The use of gas violated existing international agreements such as the Hague Conventions, which had sought to limit the use of chemical weapons.
In the days that followed, both sides began to develop countermeasures. Improvised solutions, such as cloths soaked in urine held over the mouth and nose, were initially used to neutralize chlorine’s effects. Soon after, more effective gas masks were developed and issued to troops on all sides.
The attack at Ypres marked the beginning of large-scale chemical warfare in World War I. Although it did not produce the decisive breakthrough the Germans had hoped for, it ushered in a new and brutal phase of the conflict. Over the next years, both sides would deploy increasingly sophisticated and deadly gases, including phosgene and mustard gas, leading to hundreds of thousands of casualties and leaving a lasting legacy of suffering among those who survived.
