French tear-gas use preceded Germany's large-scale poison-gas attacks in 1915. British forces developed their own capability, and a September 1915 attempt exposed British troops to their own gas. Chemical warfare spread through several belligerents rather than remaining the practice of one army. Pesticides and industrial by-products later complicated the distinction between civilian chemical production and military capability.
Notable Point · 3:20:39-3:24:25
How chemical warfare escalated during the First World War
French tear-gas use preceded the large German poison-gas attacks of 1915, followed by British adoption and further escalation.