The question of whether Ireland had been conquered by England has received some attention from historians of eighteenth-century Ireland, mainly because it preoccupied William Molyneux, author of the influential The Case of Ireland . . . Stated (1698). Molyneux defended Irish parliamentary rights by denying the reality of a medieval conquest of Ireland by English monarchs, but he did allow for what could be called ‘aristocratic conquest’. The seventeenth century, too, had left a legacy of conquest, and this paper examines evidence of consciousness among Irish Protestants of descent from ancestral conquerors. It considers how and why this consciousness took a more pronounced sectarian turn during the 1790s. Williamite anniversaries, increasingly associated with the Orange Order, became identified in the Catholic mind as symbolic reminders of conquest. Thanks to the protracted struggle for ‘Catholic emancipation’, this issue continued to feature in political debate about Ireland well into the nineteenth century, while the passing of the Act of Union (1800) revitalised the older debate about whether England could be said to have conquered Ireland. Liberal Protestants and Catholics contended that England had invariably intervened to prevent any possibility of reconciliation between conquerors and conquered.Thus the language of conquest remained highly adaptable.