The Anglo-Irish War of 1919–21 spurred organized political activity among women in Britain, including former suffragists who campaigned against coercion in Ireland and members of the Irish minority in Britain who supported more radical republican efforts to achieve Irish independence. Their efforts are particularly significant because they occurred immediately after the granting of partial suffrage to women in 1918. This article argues that the advent of female suffrage changed the landscape of women's political mobilization in distinct ways that were made visible by advocacy on Ireland, including the regendering of the discourse of citizenship and the creation of new opportunities beyond the vote for women to exercise political power. At the same time, the use of women's auxiliary organizations and special meetings and the strategic blurring of the public and private spheres through the political use of domestic spaces all indicate the strength of continuities with nineteenth-century antecedents. The article further situates women's political advocacy on Ireland in an imperial and transnational context, arguing that it was part of the process of reconceptualizing Britain's postwar global role whether through outright anti-imperialism, in the case of Irish republicans, or through humanitarianism and the new internationalism, in the case of most former suffragists. Finally, the article examines the failure of these two groups of women to forge alliances with each other, underscoring the ways in which both class and nationality challenged a notional common interest based on sex.