How different were the circumstances under which he again resumed the war against Spain! The resources of France had been squandered, the armies of France had become demoralised, the authority of the government weakened, while Spain had profited by the difficulties of her enemy to recover the Netherlands and Catalonia, and, through the treason of Condé, was enabled to place one of the best generals of the day at the head of her armies. In 1653 he invaded France and threatened Paris, but was foiled by the superior strategy of Turenne, and obliged to retreat. In the three following years France slowly won back the frontier towns of the Netherlands. It was clear that neither side was able to inflict upon the other such a defeat as would end the war. [Sidenote: =Alliance between Mazarin and Cromwell, 1657.=] So in 1656 Mazarin, cardinal and absolutist though he was, sought for the alliance of Cromwell, the Protestant hero of the English revolution. Cromwell looked upon Spain with the eyes of Elizabeth, and saw in her but the chief supporter of Popery in Europe, and the chief obstacle to English trade. An agreement was soon arrived at by which 6000 of Cromwell’s soldiers, probably the best in Europe, were put at the disposal of Mazarin. In 1657 a change was quickly perceived in the war. Turenne, with the assistance of his new allies, defeated the Spaniards at the battle of the Dunes, captured Mardyke and Dunkirk, which was handed over to England, and overran the country almost up to Brussels in June 1658. This blow determined the Spanish government to treat for peace. Conferences were held between the ambassadors of the two countries on the Bidassoa during 1659, and on November 7th the peace of the Pyrenees was signed. [Sidenote: =The Peace of the Pyrenees, 1659.=] By it France acquired Artois, Roussillon, and Cerdagne, and the towns of Thionville, Landreçies, and Avesnes. She agreed to restore the duke of Lorraine to his duchy, on condition that the fortifications of Nancy were destroyed, and the armies of France allowed free passage through the country. Condé was pardoned and restored to his property and dignities. Finally the alliance was cemented by the marriage of Louis XIV. to Maria Theresa, the daughter of Philip IV., who on her marriage renounced on the part of herself and her children all claim to the throne of Spain, on receipt of a dowry of 500,000 crowns. This dowry was never paid, and in consequence it became a question whether the renunciation was of any effect at all. [Sidenote: =Commanding position of France, 1660.=]