The government’s incursion into the midlands lordships of the O’Connors and O’Mores in 1546 is often identified as the root of the Tudor conquest of Ireland. Conversely, the years from 1535 to 1546 have been depicted as a period wherein a conciliatory approach to Gaelic Ireland was favoured. This paper argues that the origins of the Tudor conquest lie in the 1530s following the Kildare Rebellion. At this time a majority of senior officials in Ireland urged the regional conquest of the lordships of the O’Byrnes, O’Tooles and MacMurrough Kavanaghs in Wicklow and Carlow. This strategy was not adopted as Henry VIII refused to finance such a costly endeavour. Consequently a cheap political alternative now known as ‘surrender and regrant’ was briefly adopted in the early 1540s. However in 1546 the officials who favoured regional intervention in Leinster succeeded in initiating an incursion into the midlands. In light of the links between the campaign for the reduction of south Leinster in the 1530s and the incursion into the midlands in 1546, this paper argues that the origins of the Tudor conquest of Ireland can be traced to the campaign for the reduction of south Leinster in the mid-1530s.