This chapter focuses on Mazzini's profound effect on Irish political life. As elsewhere in Europe, Mazzini, with his vision of Italian nationalism, was influential in Ireland, despite his own doubts about the reality of Irish nationality. At least some Irish nationalists found in Mazzini's account of Italy under foreign rule echoes of Ireland's own experience in the United Kingdom. In 1848, for example, a group called Young Ireland attempted a rebellion against British rule. Despite the apparent similarity with other parts of Europe that also experienced nationalist revolts more or less influenced by Mazzinian ideas and models, in Ireland Mazzini's influence took a radically different turn from 1848. In Irish circumstances, no nationalist movement could hope for long-term success without the support of the Roman Catholic Church. The paradox was that that Church was both Irish and transnational; it had direct experience of Mazzini and the consequences (for the Church) of Mazzinian ideas in Italy. The course – and essential failure – of Irish nationalism in the mid-Victorian period can be traced to the influence of Mazzini on the minds of Catholic bishops who saw Irish events through Italian eyes.