The policy of Sweden had long been directed to the acquisition of possessions on the opposite coast of the Baltic, a policy which Oliver had more recently followed on a smaller scale with regard to the lands beyond the Channel. With a territory more thinly populated and poorer than that of England, the Kings of Sweden had, like the Commonwealth and Protectorate, gathered an army too large to be supported except by offensive war. The command of the Baltic Sea was the object in view, and in 1648, at the end of the Thirty Years' War, Sweden found herself in possession, not merely of Finland and the coast districts as far south as Riga, but of Western Pomerania, of the port of Wismar and of the secularised Bishoprics of Bremen and Verden. It was a policy even more provocative than that pursued by Oliver, because it concerned not merely the possession of a solitary point beyond the sea, but the possession of territories commanding the mouths of such rivers as the Oder, flowing into the Baltic, and the Elbe and the Weser, flowing into the North Sea. In 1655 the warrior-king, Charles X., who in the year before had succeeded to the Swedish throne upon the abdication of Christina, plunged into a war with Poland, which threatened to give him the command of the Vistula as well. In all this England had an interest because it was of great importance to her that the whole trade of the Baltic, whence she derived the materials without which she would have been unable to send her fleets to sea, should not pass entirely into the hands of one great military Power. It was this view of the case which commended itself to the Dutch, and led in 1656 to their sending a fleet into the Baltic to preserve the independence of Dantzic. Such a view could not be lost sight of by Oliver, but it was not in his nature to content himself with the chase after purely material interests. Ever since the summer of 1655, when Charles X. made overtures for his alliance, the Protector had been striving to give to it the character of a general Protestant League for the purpose of striking a blow at the German branch of the House of Austria. Oliver's whole scheme can only be described as the product of consummate ignorance--ignorance in supposing that Charles X., aggressive, self-centred and careless of everything but his own interests as a king and as a soldier, was another Gustavus Adolphus--or rather another such disinterested enthusiast as Gustavus Adolphus appeared in the imagination of Englishmen--ignorance too in fancying that either Austria and Poland on the one hand, or Brandenburg and Denmark on the other, were likely to govern their movements by religious rather than by political motives.