Second Battle of Ypres (1915): The First Poison Gas Attack

The Second Battle of Ypres was fought between 22 April and 25 May 1915 around the Belgian town of Ypres (Ieper). It began with the first large-scale use of lethal poison gas in history, when German troops released clouds of chlorine against French positions north of the town. Canadian, British and French troops managed to stop the German advance, but chemical warfare had become a permanent part of the First World War.

Background: the Ypres salient

After the First Battle of Ypres in autumn 1914, Allied forces held a bulge, or salient, in the line around Ypres. It was the last significant part of Belgium not under German occupation. Because the salient pushed into German-held territory, German artillery could fire into it from three sides.

In early 1915 the German army was concentrating its main effort on the Eastern Front. On the Western Front it wanted a limited operation that could also test a new weapon. The chemist Fritz Haber, head of the Kaiser Wilhelm Institute for Physical Chemistry in Berlin, proposed releasing chlorine gas from cylinders and letting the wind carry it over enemy lines. Germany argued that this did not breach the 1899 Hague declaration banning projectiles filled with asphyxiating gas, since the gas was not fired in shells.

The gas attack of 22 April

Thousands of cylinders were dug into the German line north of Ypres, near Langemarck. After weeks of waiting for a favourable wind, the gas was released at about 17:00 on 22 April 1915. Roughly 150 to 170 tonnes of chlorine formed a greenish-yellow cloud that drifted towards the French 45th (Algerian) Division and 87th Territorial Division.

Chlorine attacks the lungs and eyes, causing choking and, in heavy doses, death. The French and colonial troops had no protection. Many were overcome; others fled. Within an hour a gap of about six to seven kilometres had opened in the Allied line.

German infantry advanced behind the cloud, wearing simple protective pads. They took several kilometres of ground but stopped at nightfall, partly because they lacked reserves and were wary of entering their own gas.

The Canadian stand

The 1st Canadian Division, commanded by Lieutenant General Edwin Alderson, held the line immediately to the right of the gap. Overnight on 22-23 April, the Canadian 10th and 16th Battalions counter-attacked at Kitchener’s Wood, suffering heavy losses but helping to slow the German advance.

On 24 April the Germans released gas again, this time directly against the Canadians near St Julien. Soldiers tried to protect themselves with handkerchiefs or cloths soaked in water or urine. The Canadians were pushed back but did not break, and British reinforcements rushed in to close the gaps. The division lost about 6,000 men, around a third of those engaged, in its first major battle.

The battle continues

The fighting is divided into four phases: Gravenstafel Ridge (22-23 April), St Julien (24 April-4 May), Frezenberg Ridge (8-13 May) and Bellewaarde Ridge (24-25 May). British and French counter-attacks to regain ground were costly and largely unsuccessful.

General Sir Horace Smith-Dorrien, commanding the British Second Army, recommended pulling back to a shorter line closer to Ypres. The commander-in-chief, Sir John French, rejected the advice, handed the salient to General Herbert Plumer and soon removed Smith-Dorrien altogether. Plumer then carried out a similar withdrawal in early May. Further gas attacks followed, the last on 24 May. When the battle ended, the salient had shrunk to within about 5 kilometres of Ypres, and the medieval town was being steadily destroyed by shellfire.

Key people

• Albrecht, Duke of Württemberg commanded the German Fourth Army, which launched the offensive.
• Fritz Haber organised the gas attack. His wife, the chemist Clara Immerwahr, took her own life on 2 May 1915; how far she opposed his work is still discussed by historians.
• Horace Smith-Dorrien lost his command after advising withdrawal.
• Herbert Plumer took over the Ypres front and later became one of Britain’s most respected generals.
• John McCrae, a Canadian artillery surgeon, wrote the poem In Flanders Fields during the battle.

Consequences

Gas did not deliver a breakthrough, but it changed the war. Within weeks both sides were developing protective masks, starting with simple pads and hoods. Britain used chlorine for the first time at the Battle of Loos in September 1915. Later in the war the armies introduced more deadly gases, including phosgene and mustard gas, delivered mostly by artillery shells.

For Canada, Second Ypres became a defining moment of national pride. For France, the collapse of the colonial and territorial divisions on 22 April was a painful episode. The Ypres salient would see one more great offensive at the Battle of Passchendaele in 1917.

Myths and facts

Myth: Ypres saw the first gas of the war. Irritant gases had been tried earlier. French troops used tear-gas grenades in 1914, and in January 1915 the Germans fired shells filled with xylyl bromide, a tear gas, at Russian troops at Bolimów in Poland; the cold weather made it almost useless. What made 22 April different was the use of a lethal gas on a large scale, released from cylinders rather than fired in shells.

Myth: gas was the great killer of the First World War. Gas caused terror and lasting injuries, but artillery and machine guns killed far more soldiers. Common estimates put total gas casualties in the war at around 1.3 million, of whom roughly 90,000 died, out of about 10 million military deaths overall. Its importance lay in its psychological effect and in the long-term damage to survivors’ lungs and eyes.

Fact: masks came quickly. Within days British and French soldiers were issued with improvised mouth pads, and by the summer of 1915 cloth hoods soaked in chemicals were in use. Gas masks became standard equipment on both sides.

Fact: Ypres itself was ruined. The town’s civilians were evacuated during the battle as German heavy guns pounded it. The great medieval Cloth Hall, already damaged in 1914, was reduced to a shell. After the war Ypres was rebuilt, and the Menin Gate memorial, unveiled in 1927, now lists more than 54,000 British and Commonwealth soldiers who died in the salient and have no known grave.

By the numbers

Casualty figures come from official histories and are approximate. Early wartime claims of 5,000 gas deaths on the first day are now considered exaggerated, and the true number is unknown.

Timeline

• 1915, 22 April, about 17:00: German troops release chlorine north of Ypres.
• 1915, 22-23 April: Canadian counter-attack at Kitchener’s Wood.
• 1915, 24 April: Second gas attack against the Canadians near St Julien.
• 1915, 27 April: Smith-Dorrien is ordered to hand over the defence of the salient to Plumer; he leaves his army command in early May.
• 1915, 3 May: John McCrae writes In Flanders Fields.
• 1915, 8-13 May: Battle of Frezenberg Ridge.
• 1915, 24-25 May: Battle of Bellewaarde Ridge; the offensive ends.

Why it matters

Second Ypres marked the start of modern chemical warfare. It showed that science and industry could create new weapons of mass injury, prompting the gas masks, protective drills and later international bans that followed. Its memory lives on in Canada and in the poppies of In Flanders Fields.