What was significant about the Second Battle of Ypres?

The Second Battle of Ypres, fought from April to May 1915 during World War I, was significant for being the first major battle in which poison gas was used as a weapon, marking a new and terrifying phase of warfare. The German forces released chlorine gas, causing panic and suffering among the Allied troops, who were unprepared for such an attack. This battle also highlighted the horrors of trench warfare and the need for advancements in protective gear, leading to the development of gas masks. Ultimately, the battle set a grim precedent for the use of chemical weapons in subsequent conflicts.