During the German Spring Offensives of 1918, also known as the Ludendorff Offensives and Operation Michel, the Germans used chemical weapons to an extent never seen before, or since, on the battlefield. During the largest artillery bombardment, and chemical attack, in history, Mustard ran in the gutters of the French village of Armentiers "like rain." CBRNPro.net explores this tactical innovation, and what followed in the second part of its ongoing series re-examining the history of chemical warfare, and the lessons that history can teach us today.