Several European powers regarded the
Baltic Sea as of vital importance. 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. Initially Denmark had the upper hand, but eventually it lost ground to Sweden. Neither Denmark nor Sweden managed to realize thorough military and economic control of the Baltic, though Sweden during
its time as an empire came closest to that aim before the
Great Northern War of 1700–1721.
Danish dominium maris baltici Historiography uses the term
dominium maris baltici either in a narrower sense as a new Swedish concept of the Early Modern era, closely tied to the
Swedish Empire, or in a wider sense including the preceding Danish hegemony in the southern Baltic Sea. 1168-1227 Denmark had subdued the southern Baltic coast from Holstein to Pomerania in the 12th century, but lost control in the 13th century after being defeated by German and Hanse forces in the
Battle of Bornhöved (1227), retaining just the
principality of Rügen. Thereafter, the
Hanseatic League became the dominant economic power in the Baltic Sea. Atterdag's daughter and
de facto successor,
Lady Margaret, managed to concentrate the crowns of Denmark,
Norway and
Sweden in her
Copenhagen-centered
Kalmar Union from 1397. In 1429, Kalmar king
Eric of Pomerania started to raise the
Sound Dues from merchants entering or leaving the Baltic Sea, allowing the Copenhagen court to benefit from the Baltic Sea trade profits
without engaging in economic adventures itself. The Sound Dues, imposed until 1857 and constituting a primary source of income for the Royal treasury, quickly became a contentious issue, which brought Denmark into conflict with the Hanseatic League and the neighboring powers. After the break-up of the Kalmar Union in the early 16th-century, the
Kingdom of Sweden became
Denmark–Norway's primary rival for hegemony in the Baltic Sea.
Christian IV of Denmark's victory in the
Kalmar War in 1613 marked the last instance of a successful defense of a Danish
dominium maris baltici against Sweden; subsequent wars ended in Sweden's favor. The period of Danish intervention in the
Thirty Years' War of 1618–1648 (
Kejserkrigen of 1625–1629) is also considered part of the wars for the
dominium maris baltici—in this war, however, the opponent was not the Swedish king, but the ambitious
Holy Roman Emperor Ferdinand II, who temporarily planned to establish the Empire as a naval power in the Baltic. He assigned this task to
Albrecht von Wallenstein, leading to a concerted action by Denmark and Sweden in the
defense of Stralsund. The Danish defeat in the
Battle of Wolgast (1628) and the subsequent
Treaty of Lübeck in 1629, however, removed Denmark from the battlefield.
Swedish dominium maris baltici After Sweden had left the Kalmar Union in 1523, she became Denmark's major rival for the
dominium maris baltici. The first war ascribed to this conflict is the
Northern Seven Years' War (1563–1570, associated with the
Livonian War), which between 1611 and 1613 followed the above-mentioned
Kalmar War. and the
Swedish landing in Pomerania in 1630. Since the Thirty Years' War, Sweden collected customs (
Licenten) from merchant vessels on the Baltic Sea, in Swedish as well as in non-Swedish ports. These customs were calculated as a certain percentage of the value of transported goods, and once payment took place in any port, the respective receipt was valid for the whole
dominium maris baltici. The
Second Northern War, the
Scanian War and the
first stage of the
Great Northern War left Sweden's
dominium maris baltici intact, yet it was finally ended by the
Treaty of Nystad in 1721. ==Aftermath==