Chapter 2 shows how the arrival of lethal chemical warfare at the Second Battle of Ypres in April 1915 led to the invention of anti-gas protection. It traces the crucial role played by women in this initial process and how the prospect of gas masks for civilians slowly emerged during the First World War and then continued in the war’s aftermath. The prospect of a future war of aero-chemical annihilation motivated feminist antimilitarists and others demanding the curtailment of chemical arms. Nonetheless Britain continued in both the metropole and empire to develop both such weapons and equipment to protect individuals from poison gas. Chemical weapons also had defenders, and the debate over their legitimacy played out in public even as government officials, who were inventing civil defense in secret in the 1920s, incorporated individual anti-gas protection into their calculations.

Chapter 5 demonstrates how the league of nations became an important political issue in 1917–1918. While the pro-league movement succeeded in attracting public attention for the post-war plan, pro-leaguers came to promote a conception of the league that they had opposed in 1914–1915: a league of victorious powers aligned against Germany. Begun as a reaction against anti-German jingoism and the balance-of-power politics, the movement initially aspired to change the norms of international relations by creating a new institution comprised of all the great powers. Yet by 1918, the activists had come to promote the league as a continuation of the war-time alliance, backed by a powerful argument both to defeat Germany and to form the league as a coalition of democratic states. An extension of the war-time politics, not the yearning for peace as scholars have supposed, led to the creation of the League of Nations.