Patrick J. Mahoney, The Fenian Empire: A Hemispheric History of Irish Republican Nationalism (NYU Press, 2026).

In the aftermath of the American Civil War, the Fenian movement stood at a crossroads. Thousands of demobilized Irish American soldiers hoped that the experience and training they had garnered during the late war might aid their attempts to bring about Irish independence. Yet many individual Fenians came to view their cause through an internationalist lens, placing their desired Irish republic on the front lines of an ideological fight against monarchy and aristocracy in the western hemisphere.

Fueled by a popular desire for republican expansion, the period saw the unlikely emergence of Black Fenian volunteers, attempts to land Fenian troops into Mexico and Cuba, and the participation of many Fenians in the subjugation of Native peoples along the western plains of North America. 

Drawing on an expansive range of archives and sources across multiple languages, Mahoney delivers a fresh take on the Fenian story, guiding readers through a world of clandestine meetings, personal networks, propaganda, and long-forgotten military operations.

Initial reviews:

“Teeming with individual Fenians, splits, spies, and swagger, it is a captivating read contending with ideas which are at once both historical and contemporary.” ~Úna Ní Bhroiméil, author of Building Irish Identity in America 1870-1915

“The Fenian Empire will be regarded as a significant contribution to the study of Fenianism and, more broadly, of the Irish in mid-19th-century America.” ~Kerby Miller, author of Emigrants and Exiles: Ireland and the Irish Exodus to North America

“Meticulously-researched in unfamiliar archives and sources, Patrick J. Mahoney’s innovative book opens up important new vistas on the history of global Irish nationalism and expands debates about the Irish diaspora and colonialism in the nineteenth century.” ~Niall Whelehan, University of Strathclyde

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