Hans Willem Bentinck, 1st Earl of Portland (1649-1709) was the closest confidant of William III and arguably the most important politician in Williamite Britain. Beginning his career in 1664 as page to William of Orange, his fortunes gained momentum with the Prince’s rise to power in The Netherlands and Britain, emerging as William’s favourite at court from the 1670s onwards. Taking a broadly chronological approach, the central concern of this book is not simply to provide a biographical account of Portland’s life, but to explore wider political themes within a European context. By analysing Portland’s role within William’s government it shows how royal favourites could still wield considerable influence on European events and help shape royal policy, particularly with regard to foreign policy. By engaging with the question of why such a figure emerged, this study helps illuminate the workings of William’s government and the central role of his foreign entourage. Drawing from archival material in England, Scotland, France and The Netherlands, it ties the history of post-Revolution Britain with political events in the Netherlands. It also analyses Anglo-Dutch political relations during the crucial period of the Nine Years War, Britain’s first major commitment to a continental war since the sixteenth century. In so doing it connects Dutch and British historiography and significantly contributes to our understanding of British politics during the 1690s, both domestically and within an international context.