The History of the O’Dwyers, originally published in 1933 as The O’Dwyers of Kilnamanagh: The History of an Irish Sept, is a comprehensive historical and genealogical study written by Sir Michael Francis O’Dwyer (1864–1940).

The book documents the long history of the O’Dwyer clan, a Gaelic Irish family who held influence over the region of Kilnamanagh in County Tipperary for centuries. It traces their lineage from early Gaelic origins through the medieval period, the Anglo-Norman invasions, and the upheavals of the Tudor and Cromwellian eras.

A major focus of the work is the clan’s political and military role in Munster, including conflicts with English rule, shifting alliances, and the eventual loss and redistribution of their ancestral lands during the 17th century confiscations. The book also explores the later diaspora of the family, including migration into Irish military service in continental Europe.

Key themes include:

• Origins and genealogy of the O’Dwyer clan (Ó Duibhir)
• Gaelic lordship in Kilnamanagh, County Tipperary
• Medieval Irish clan structures and territorial control
• Conflicts during the Tudor conquest and Cromwellian settlement
• Loss of estates and transplantation after 17th-century upheavals
• Irish military diaspora in France and Spain
• Clan survival and identity through political change
• Historical geography of Munster families

The work is based on family records, historical documents, and genealogical reconstruction, combining narrative history with lineage analysis. It is often regarded as one of the more detailed early 20th-century clan histories written from within the Anglo-Irish administrative elite.

Beyond genealogy, the book reflects the author’s broader interest in Irish history and imperial administration. Sir Michael O’Dwyer, a former Lieutenant Governor of Punjab, produced the work late in his life, contributing to both historical writing and political commentary of his era.

Although primarily a clan history, the book also provides insight into broader Irish historical processes, including land confiscation, colonial governance, and the transformation of Gaelic society under English rule.

Today, it is used as a reference source in Irish genealogy, local history, and clan studies, particularly for those tracing the O’Dwyer lineage or studying Gaelic family structures in Munster.