While the territories ruled by the Swedish crown had still to reach their greatest extent, the peace of Westphalia established Sweden as the leading power in the Baltic. This had come about as the result of a combination of factors: the need to counter the ambitions of successive Danish rulers to reimpose the control they had exercised during the period of the Kalmar Union and more recently of the Vasa kings of Poland to gain their inheritance; the distraction of other great powers in the religious struggles of western and central Europe and the interest of the Maritime Powers in limiting Denmark’s naval domination of the Baltic; the leadership of men like Gustavus Adolphus and Axel Oxenstierna; and the economic resources which compensated to a certain extent for the general poverty of the country. While certainly success bred ambition, it is difficult to see in the growth of Swedish power the evolution of a deliberate imperial plan for Baltic domination for longer than brief periods. It was, as with the foreign policy of most nations, a matter of using changing opportunities to pursue what were seen at the time as the best interests of the country. Oxenstierna in particular for a time did seem to have glimpsed the possibility of securing control of all the main export outlets in the Baltic, but all this belongs to a rather late stage in the development of the ‘empire’. It re-emerges under Charles X and Charles XII, but permanent control of the Prussian ports and in particular Danzig, which is the only way such a monopoly could have been effective, always eluded the Swedes.1