The making of the international system from c. 1500 reflected distinctively maritime dynamics, especially “gunboat diplomacy,” or the use of naval force for commercial gain. Comparisons between civilizations and across time show, first, that gunboat diplomacy was peculiarly European and, second, that it evolved through stages. For the majority of the modern era, violence was central to the commercial strategies of European state, private, and hybrid actors alike in the wider world. In contrast, large and small non-Western polities almost never sought to advance mercantile aims through naval coercion. European exceptionalism reflected a structural trade deficit, regional systemic dynamics favoring armed trade, and mercantilist beliefs. Changes in international norms later restricted the practice of gunboat diplomacy to states, as private navies became illegitimate. More generally, a maritime perspective suggests the need for a reappraisal of fundamental conceptual divisions and shows how the capital- and technology-intensive nature of naval war allowed relatively small European powers to be global players. It also explains how European expansion and the creation of the first global international system was built on dominance at sea centuries before Europeans’ general military superiority on land.