April 22, 1915

Second Battle of Ypres

German chlorine attack opens the Second Battle of Ypres

The German engineers waited through seven aborted attempts for the wind to turn — then opened 5,730 cylinders buried along six kilometres of trench.

A green-yellow cloud, not an invisible one

In the late afternoon of 22 April 1915, near Langemarck north of Ypres in Belgium, German specialist troops released about 150 tons of chlorine from cylinders along roughly six kilometres of front.

The cloud was conspicuous: witnesses and historical accounts describe it as green-yellow, not invisible. It struck the French 45th Algerian Division to the Canadians' left, and soldiers suffocated or fled with burning eyes and throats.

A gap several kilometres wide opened in the line, exposing the Canadian flank.

An opening the attackers were not ready for

German infantry advanced behind the cloud, but the German command had not provided enough reserves to exploit the unexpected breakthrough. After about two kilometres the attackers were checked by an improvised Allied response.

By evening German forces had captured more than 1,800 French and 10 British unwounded prisoners, over 51 guns and about 70 machine guns, with a wide gap still open.

Urine-soaked cloths were a documented emergency expedient when anti-gas solution ran out, but they were not an effective respirator; the line held through several interacting factors, including German delay, inadequate German reserves, Allied repositioning and counterattacks.

First at this scale, not first of the war

This was the first large-scale battlefield use of lethal poison gas, not the beginning of chemical warfare. France had used tear-gas grenades in 1914, and Germany had already fired irritant shells at Neuve-Chapelle and Bolimów.

The 22 April cloud primarily struck French colonial and territorial formations. The better-known direct gas attack on Canadian positions came on 24 April.

Casualty figures are disputed: modern scholarly estimates commonly give roughly 1,000–1,100 deaths and 4,000–7,000 injuries, while older claims of 5,000 dead and 15,000 casualties may combine the attacks of 22 and 24 April and are probably inflated.

Sources

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What the sources leave uncertain

The date and nature of the attack are secure, but casualty figures are highly disputed. Modern scholarly estimates commonly give roughly 1,000–1,100 deaths and 4,000–7,000 injuries; older claims of 5,000 deaths and 15,000 total casualties may combine the attacks of 22 and 24 April and are probably inflated.
Sources variously describe a six-, 6.5- or seven-kilometre release front, reflecting measurement and rounding differences.