About this time Holland was strengthened by the alliance of Spain, and the Emperor Leopold, alarmed at the continual invasions of German territory on the Upper Rhine, ordered Montecuccoli to make war in earnest. In 1674 the Diet formally declared war against France, and Frederick William marched with 16,000 men to the Palatinate, which Marshal Turenne had ravaged with fire and sword. The French were driven back and even out of Alsatia for a time; but they returned the following year, and were successful until the month of July, when Turenne found his death on the soil which he had turned into a desert. Before this happened, Frederick William had been recalled in all haste to Brandenburg, where the Swedes, instigated by France, were wasting the land with a barbarity equal to Turenne's. His march was so swift that he found the enemy scattered: dividing and driving them before him, on the 18th of June, 1675, at Fehrbellin, with only 7,000 men, he attacked the main Swedish army, numbering more than double that number. For three hours the battle raged with the greatest fury; Frederick William fought at the head of his troops, who more than once cut him out from the ranks of the enemy, and the result was a splendid victory. The fame of this achievement rang through all Europe, and Brandenburg was thenceforth mentioned with the respect due to an independent power. [Sidenote: 1677.] Frederick William continued the war for two years longer, gradually acquiring possession of all Swedish Pomerania, including Stettin and the other cities on the coast. He even built a small fleet, and undertook to dispute the supremacy of Sweden on the Baltic. During this time the war with France was continued on the Upper Rhine, with varying fortunes. Though repulsed and held in check after Turenne's death, the French burned five cities and several hundred villages west of the Rhine, and in 1677 captured Freiburg in Baden. But Louis XIV. began to be tired of the war, especially as Holland proved to be unconquerable. Negotiations for peace were commenced in 1678, and on the 5th of February, 1679, the "Peace of Nymwegen" was concluded with Holland, Spain and the German Empire--except Brandenburg! Leopold I. openly declared that he did not mean to have a Vandal kingdom in the North. Frederick William at first determined to carry on the war alone, but the French had already laid waste Westphalia, and in 1679 he was forced to accept a peace which required that he should restore nearly the whole of Western Pomerania to Sweden. Austria, moreover, took possession of several small principalities in Silesia, which had fallen to Brandenburg by inheritance. Thus the Hapsburgs repaid the support which the Hohenzollerns had faithfully rendered to them for four hundred years: thenceforth the two houses were enemies, and they were soon to become irreconcilable rivals. Leopold I. again betrayed Germany in the peace of Nymwegen, by yielding the city and fortress of Freiburg to France.