While the modern military gas mask was first designed by scientists such as Richard Willstätter in order to save German soldiers from chemical death, it ultimately contributed to the escalation of chemical warfare in World War I. New military tactics and advances in chemical weaponry such as gas shells and mustard gas were developed with the express purpose of “breaking the mask.” Thus, the gas mask was part and parcel of both the war of sheer material production and the chemical nightmare on the battlefield that helped precipitate the German defeat in 1918. By intertwining the historical development of gas with that of the gas mask, this chapter highlights moments in which a specifically German “chemical modernity” began to be conceptualized.