On April 22, 1915, during World War I, the world witnessed a terrifyingly innovative and grotesque military tactic that would forever change warfare: the first large-scale poison gas attack by German forces at the Second Battle of Ypres in Belgium. Chlorine gas, a chemical weapon previously used in limited quantities, was released from nearly 6,000 pressurized cylinders along a four-mile front against French Algerian and Canadian troops.The greenish-yellow cloud, carried by light winds, crept across No Man's Land like an ethereal harbinger of death. Soldiers who initially thought it was a harmless mist soon discovered its horrific nature - the gas caused severe burning in the lungs, creating a ghastly spectacle of men choking, bleeding from their mouths, and suffocating in agony.The attack created a massive 4-mile wide gap in the Allied lines, with soldiers fleeing in panic or dying gruesome deaths. Despite the potential for a complete breakthrough, German commanders were so uncertain about the weapon's effectiveness that they failed to immediately exploit the tactical advantage.This moment marked a brutal turning point in military history, demonstrating how scientific innovation could be weaponized in unprecedented and nightmarish ways. The Geneva Protocol would later ban chemical weapons, but not before they had unleashed unimaginable suffering on battlefields across the world.