Unlike World War I, where gas was used frequently on the Western Front, World War II didn't see much use of chemical weapons. However, they didn't know that at the time. The major reason is that chemical weapons didn”t have effective means of delivery, and they were hard to handle. Also, if smoke or fire obscured the tunnels, the gas masks might provide some relief. This training poster was placed on the corrugated metal wall of the Annexe Hospital.