The history of Ireland is complex, and has been plagued with religious, political and military influences that have created divisions within its population. Ireland's experience throughout the French Revolutionary and Napoleonic Wars highlighted and intensified such divisions that have influenced Irish society into the twenty-first century. This body of work is an analysis of the British army in Ireland during the period 1793 to 1815, which proved to be a critical era in British and Irish history. The consequences of the events and government policies of that time helped to determine the social and political divisions within Ireland for the following two centuries. The intention of this thesis is to provide an analytical synthesis of the military history of Ireland during this time, focusing on the influences, experiences and reputations of the various elements that comprised the Irish military forces. This revisionist study provides an holistic approach by assessing the militia, yeomanry, fencible and regular regiments in relation to their intended purpose within Britain's strategy. By focussing on deployment, organization, performance, leadership and reputations, as well as political and military background, a number of perpetual misconceptions have been exposed, especially in relation to the negative historiography surrounding the Irish militia and yeomanry due to sectarian bias. This work shows that Ireland became an important facet of the tactical and strategic thinking of both the French and British governments at this time, with Britain needing to defend the kingdom against any possible invasion to secure its own defence. This resulted in the British military occupation of a kingdom whose population had been polarised by civil rebellion, invasion and renewed religious bigotry. A close examination of the military history of the kingdom during these crucial years provides a better understanding of how the Irish became, and remained, a socially and politically divided people, while being subjected to the political and military dominance of Britain.