Following the Germans’ first use of chlorine gas during the second battle of Ypres, the Entente had to develop means of protection from future poison gas attacks as well as systems for retaliation. This article, through the analysis of heretofore unexamined archival sources, considers early French attempts at engaging in chemical warfare. Contrary to the existing historiography, the French army aggressively adapted to, and engaged in, chemical warfare. Indeed, the French army would be the first to fire asphyxiating gas shells from field guns and, by June 1915, would pioneer the use of gas as a neutralization weapon to be used in counter-battery fire, as opposed to unleashing gas via canisters to engage enemy infantry. Such innovation invites a rethinking not only of French gas efforts but also of the role and evolution of the French army as a whole on the Western Front, a topic which the Anglophone world is in great need of examining further.