While the Germans waited for the gas to disperse, Canadian forces were sent in to fill the gap. A medical officer (there is some debate as to which one, exactly) saw the greenish cloud approaching and identified the weapon. Then, thinking quickly, he spread word to the troops, advising them to urinate in cloths and hold them up to their faces.
Whoever he was, we feel we can unequivocally state at this point that the medical officer in question was either the most beloved man on the battlefield or the most feared, because the troops quickly obeyed and basically pissed all over their own faces at just his say-so. And that’s what saved all of their lives: The urea in urine reacted with the chlorine, effectively neutralizing the deadly gas. The Canadians were able to hold the Germans back until British reinforcements arrived. And though they suffered nearly 50 percent casualties defending Ypres, they successfully held the Germans off with the power of pee.