Dominium maris baltici

The establishment of a dominium maris baltici (Latin: [doˈminium ˈmaris balˈtitʃi], "Baltic Sea dominion") was one of the primary political aims of the Danish and Swedish kingdoms in the late medieval and early modern eras. Throughout the Northern Wars the Danish and Swedish navies played a secondary role, as the dominium was contested through control of key coasts by land warfare.

The term, which is commonly used in historiography, was probably coined in 1563 by the king and grand duke of the Polish-Lithuanian union, Sigismund II Augustus, referring to the hegemonial ambitions of his adversaries in the Livonian War. The first written reference stems from the Dutch-Swedish treaty of 5 (O.S.) / 15 (N.S.) April 1614, concluded in The Hague.

Several European powers regarded the Baltic Sea as of vital importance. It served as a source of important materials and as a growing market for many commodities. So large did the importance of the region loom that it became of interest even to powers that did not have direct access to it, such as Austria and France. For several centuries, Sweden and Denmark would attempt to gain total control of the sea, a policy which other local and international powers opposed. Historians have described the control of the Baltic as one of the main goals of Denmark's and Sweden's policies.

The Scandinavian (Nordic) powers, who sensed opportunity in the power vacuum created by the weak or non-existent naval power of the Holy Roman Empire and Poland-Lithuania, adopted expansionist policies which fostered conflict over the Baltic. Denmark and Sweden used their control of parts of the Baltic to fuel their militaries. Each claimed the Baltic as their own, and promised to protect foreign shipping. While the Nordic powers vied with one another over control, they both agreed that it should be the domain of one of them, not of an "outsider" like Poland or Russia. The Scandinavian powers tried to prevent the rise of their opposition through diplomatic treaties, which forbade other powers like Russia or Germany to build navies, and through military actions, whether targeting opponent naval forces, or through taking control of the Baltic ports. In one of the most notable actions to retain its monopoly over the Baltic, Denmark in 1637 destroyed, without declaration of war, the nascent Polish-Lithuanian Commonwealth Navy.

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