During the First World War, the Spanish Labour Movement gained steadily in strength, and by 1919 the CNT (National Confederation of Labour) had over 700,000 affiliates. However, the ascendance of the anarcho-syndicalist movement met with severe government repression, especially in Catalonia. In November 1920, the authorities unleashed an all-out offensive against the CNT, arresting members and ordering raids of union offices. Shootings between anarchists and the hired guns of the employer class occurred with increasing regularity, and anarchists were frequently arrested and tortured by the authorities. Whilst acknowledging the difficulties that militants faced during these years, and the damage that the violence did to the movement in the long term, this article assesses the ways in which militants resisted the repression, and the symbolic importance that the anarchist action groups assumed for militants in later struggles.