This book investigates the intersection of nobility, empire and dynastic change and survival through the history of one of Portugal&s most active and enduring aristocratic lineages, the Mascarenhas. Spanning four centuries of service and war, it traces how the Mascarenhas navigated shifting political contexts across three ruling dynasties, European conflict, revolutionary upheaval and civil war. During this time, in both the metropole and its empire, Portugal emerged from early modernity to the eve of the first industrial revolution. Drawing on prosopographical methodology and archival, printed primary and related secondary sources, this book bridges biographical and structural approaches to the Early Modern nobility. Through its analysis of the evolution of the Mascarenhas lineage over the longue durée and the development of its cadet branches, it provides fresh insights into the role of the aristocracy in Portugal&s imperial world.