The Duchy of Courland and Semigallia, a vassal to the Polish-Lithuanian Commonwealth and constrained at the eastern edge of the Baltic Sea, was an unlikely candidate for colonial expansion. Yet, in the mid- to late seventeenth century, the ambitions of the dukes, in particular Duke Jakob Kettler (reigned 1642-1682), provided it with a brief colonial presence in Tobago and The Gambia. The Duchy is an extreme example of a small-power coloniser, and it supplies a stark alternative to narratives of domination by Western European polities. These powers loom large in post-colonial studies of the Atlantic, in part due to their longevity as empires and their powerful effect on world history. Through the analysis of Courland, this study seeks to uncover the networks used by a weak political entity in pursuing colonial trade. It connects two spaces, the Baltic and the Atlantic in order to determine how much transfer of experience and knowledge took place between these contexts. Comparing spaces uncovers a neglected post-colonial angle to the field of Couronian colonialism, which emphasises that Courland was a colonial power in both Europe and the Atlantic. Above all the study portrays the broad range of relations and encounters involved in shaping the vassal’s fortunes outside of the Baltic. Consequently, a revision of previous historiography on Courland is needed in order to move the field away from the single metropolitan point of Duke Jakob and thereby appreciate the wider connectivity of colonial actors and experiences.