This thesis explores the ‘Irish Revolution’ through a systematic analysis of events at a regional level in Co. Leitrim between the years 1912 and 1923. Both political behaviour and military activity are examined from the introduction of the Home Rule Bill to the end of the Irish Civil War, a period of extraordinary upheaval and unrest at a national level. The contested historiography of the period is outlined, and its application to Leitrim is examined. Aside from the 1919-1923 period of intense conflict across the country, the eleven-year period between 1912 and 1923 witnessed a massive political transformation with the collapse of the Irish Party and the rise of Sinn Féin. The study examines the party machines of constitutional and advanced nationalism at local level, and ascertains whether the political motivations and operations of both factions were based on narrow parochial and personal interests, rather than social class or ideology. The motivations and social status of participants, the interconnections of political factions, and what influenced the decline of these groupings constitute a major element of the study. The effect of the First World War on the county is examined in detail. Recruitment patterns, casualties, motivation for enlisting, voluntary war work, and reactions to the war are outlined. The effect of the war on the social and economic fabric of society is also explored. A detailed examination of Leitrim’s experience of political violence in the 1919-1923 period is undertaken as part of the study. Military strategy, structures, and operations are examined in both the War of Independence and Civil War period. In summary, the thesis charts the impact on local politics and society of the linked national and international conflicts of the period, examining the consequences of the Irish revolution for a small rural community in the north west of Ireland.