Charles Gustavus however held military possession of a large part of Denmark, and in the spring began to press the attack on the capital from the land side.  As both England and France showed a disposition to interfere in the conflict, the States-General now acted with unexpected vigour, recognising that this question to them was vital.  An imposing force of seventy-five warships, carrying 12,000 troops and mounting 3000 guns, was despatched in May, 1659, under De Ruyter to the Baltic.  Negotiations for peace between the Scandinavian powers under the mediation of France, England and the United Provinces, were now set on foot and dragged on through the summer.  But neither Charles Gustavus nor Frederick could be brought to agree to the terms proposed, and the former in the autumn again threatened Copenhagen.  In these circumstances De Ruyter was ordered to expel the Swedes from Funen.  On November 24 the town of Nyborg was taken by storm and the whole Swedish force compelled to surrender.  De Ruyter was now supreme in the Baltic and closely blockaded the Swedish ports.  The spirit of Charles Gustavus was broken by these disasters; he died on February 20, 1660.  Peace was now concluded at Oliva on conditions favourable to Sweden, but securing for the Dutch the free passage of the Sound.  The policy of De Witt was at once firm and conciliatory.  Without arousing the active opposition of England and France, he by strong-handed action at the decisive moment succeeded in maintaining that balance of power in the Baltic which was essential in the interest of Dutch trade.  The republic under his skilful leadership undoubtedly gained during the northern wars fresh weight and consideration in the Councils of Europe.

The peace of the Pyrenees, followed by the peace of Oliva and the settlement with Portugal, seemed to open out to the United Provinces a period of rest and recuperation, but probably no one knew better than the council-pensionary that outward appearances were deceptive.  In the spring of 1660 a bloodless revolution had been accomplished in England, and Charles II was restored to the throne.  The hostility of De Witt and of the States party to the house of Stuart had been marked.  It happened that Charles was at Breda when he received the invitation recalling him to England.  The position was a difficult one, but the council-pensionary at once saw, with his usual perspicacity, that there was but one course to pursue.  Acting under his advice, every possible step was taken by the States-General and the Estates of Holland to propitiate the prince, who from being a forlorn exile had suddenly become a powerful king.  Immense sums were spent upon giving him a magnificent reception at the Hague; and, when he set sail from Scheveningen, deputations from the States-General and the Estates of Holland attended in state his embarkation and lavish promises of friendship were exchanged.  It was significant, however, that Charles handed to the council-pensionary a declaration commending to