In 1936 the founders of PAX aimed at 'resistance to modern warfare on grounds of traditional morality'. Believing that 'just war' criteria could no longer be met, they called themselves pacifists. Although most members were Roman Catholic Pax did not claim to be a 'Catholic society' because the RC Church at that time took an opposing view, particularly of conscientious objection. Church authorities attempted to censor Pax literature and instructed clergy to resign from the society. Pax supported conscientious objectors during the Second World War. When membership declined afterwards it continued to publish the Pax Bulletin and to provide a forum where Catholics could debate theological and practical questions of war and peace. By the 1960s Pax had gained some distinguished sponsors and a branch in the United States - support which enabled it to influence debate at the Second Vatican Council in 1965. The Council endorsed the right to conscientious objection. In 1971 Pax merged with Pax Christi, the international Catholic peace organisation which began in France in 1944/45. This is the first detailed historical study of the Roman Catholic element in the British peace movement. The story of Pax demonstrates the part that even a small pressure group can play in changing public opinion through patient work. Eventually, despite apathy and opposition, Pax helped bring the RC Church to a recognition of the right to conscientious objection and played a crucial role in the development of a more widespread peace movement within the Church