In early 1915 the two sides were deadlocked. At Ypres the front line formed a bulge around the town, known as the Ypres Salient. To break the impasse, both sides experimented with new weapons. Among them was poison gas. On 22 April 1915 the German army used poison gas on a large scale for the first time. It marked the start of the Second Battle of Ypres. Take a look at the large canister in the corner of the display case. The Germans opened thousands of canisters like that, filled with chlorine gas. A yellowish-green cloud rolled slowly across Allied positions, and the men, taken by surprise, fled retching and gasping for breath. At a stroke there was a gap in the front line six kilometres wide. It was an unexpected success, but because of poor communications and a lack of sufficient reserve troops, the German advance stalled. Furthermore, the Allies were quickly supplied with gas masks, so the chances of a future breakthrough remained small. It became clear that poison gas was not a miracle weapon that could break the stalemate; it merely increased the suffering of the ordinary soldier at the front. In this room you can smell the various kinds of poison gas for yourself. Don’t worry, the scents are completely harmless.