A major study of the Communist party of Great Britain between the wars, when it adopted the military strategy of class against class, in its struggle to be the effective alternative to both the Labour Party and the TUC. This revisionary study, based on newly-discovered material in the Manchester archive of the Communist Party, shows that far from losing influence and being driven to the brink of collapse, the CPGB then consolidated its position, led national hunger marches and organized social and cultural events, while membership grew and the party developed as an effective and valued body in the pantheon of leftwing British politics.