From the late 14th through the 15th century, the German Hanse was a major player in economic, political, and military conflict –areas traditionally associated with state actors –throughout northern Europe, despite being a decentralized, non-sovereign, non-territorial entity. The Hanse was a late medieval/early modern trade organization, the driving purpose of which, from its founding and throughout its development, was to provide for the mutual protection of its member cities’ merchants in the course of their business and ensure and expand their rights and privileges in foreign ports; to protect their merchants against the predations of both pirates and kings. It is thus one of the great historical ironies that the Hanse became a source of piracy and mercantile harassment rivaling those of the sovereign states of Northern Europe. The Hanse’s relations with England throughout the late 14th and 15th century, especially in the decades surrounding the English dynastic struggle of the Wars of the Roses and concurrent Anglo-Hanseatic War, exemplify the Hanse’s role as a state-like actor in international conflict. Current scholarship on the Hanse focuses on cliometric trade analysis and linear narrative history, but I emphasize the unique nature of the Hanse and how it determined their actions on the international stage, critically reading Parliamentary records, royal appeals, and major secondary sources in light of my analysis of the Hanse’s foundational documents. I explore the motivations of the Hanse in its conflicts with England and determine that the Hanse’s use of piracy and the harassment of English merchants represented a natural continuation of their founding principles. My research addresses questions of the motivations and internal dynamics of one of the most successful and longest-lasting international trade leagues to-date as it interacted with more traditional state-entities in diplomatic and economic contexts.