Paul Cullen was without question the most important Irishman of his generation and a figure of global importance. He is also among the least understood. Examining every aspect of Cullen's life and career, Colin Barr explores how Cullen was characterised by his contemporaries as an 'Italian monk', 'the deadly foe of Irish liberty', 'an obscurantist run mad', or 'the most malignant enemy of the English & English Government in Ireland.' One frustrated contemporary called him 'the Pope of Ireland'. This study explores Cullen's early years and education in papal Rome, his career in the curia and then in Ireland, as Archbishop of Dublin, the first Irish cardinal, and author of the compromise text that defined the dogma of papal infallibility. Drawing on more than100 archives in ten countries, The Irish Pope examines Cullen's life and work at home and abroad, and through it the history of Ireland in the mid-Victorian era.