During the second world war, war savings campaigns reframed money as a means to defend children, secure freedom, and enact citizenship across the British world. Patriotic thrift propaganda urged people to reject consumer goods and instead invest deliberately in stamps, certificates and bonds, presenting saving as a patriotic act that transformed subjects into accountable citizens. Officials and volunteers built a state-directed mobilisation that documented participation and linked household decisions to national victory. In Britain, these initiatives brought workers together and validated housewives’ expertise, while Canada and Australia developed parallel schemes. Even colonies such as Uganda invested actively in British defence. Fighting with money examines how activists constructed these campaigns, the identities they imagined and their limits in a shifting wartime and postwar landscape.