Anglophone historians are generally familiar with a handful of treatises on Tudor Ireland, notably Edmund Spenser’s A View of the Present State of Ireland. Yet it is less known that there were over six hundred of these treatises written on Ireland during the sixteenth century, and that there is substantial reason to believe that one of the most significant of these was A Breviat of the Conquest of Ireland and of the Decay of the Same written by Patrick Finglas during the reign of Henry VIII. This work of historical analysis and prescriptive policy advice was the most widely read treatise on Ireland during the sixteenth century and is a key text in the formation of the early modern British state. This paper examines Finglas’s text and argues for its critical importance in determining how officials and senior ministers viewed Ireland and formulated policy for it during the sixteenth century.