This is the definitive work on one of the most obscure and easily misunderstood episodes in the history of the United States between 1865 and 1901. Kenny demonstrates that the outbreak of Irish-related violence in the anthracite region of eastern Pennsylvania in the 1860s and 1870s was fundamentally a reflection of the area's sharpening confrontation between capital and labour. Working conditions and wages in the mines were a constant source of grievance, and there was ample scope for ethnic rivalries involving nativist Americans as well as English, Welsh and Irish immigrants. At the same time, the Irish drew on a tradition of violent protest against social conditions that was rooted in the rural areas of north-west and northern Ireland where most of them originated. The Molly Maguires of Pennsylvania were not some terrible, far-reaching conspiracy, as alleged at the time by prosecutors, Pinkerton private detectives and the press. But there was indeed a minority of Irish-born individuals willing to kill mining officials and destroy property. Public hysteria was deliberately whipped up by those, such as the railroad and mining companies, with a clear interest in breaking the union movement. As Kenny shows, the trials that led to the hangings of 20 alleged Molly Maguires were in many respects a travesty of justice. But if they suppressed "Molly Maguireism" forever, they did not stop violent assaults by public and semi-public authorities on American trade unionists for decades to come.