The campaign of 1675 offered no remarkable event; the Prince of Orange with great prudence avoiding the risk of a battle.  But the following year was rendered fatally remarkable by the death of the great De Ruyter,[7] who was killed in an action against the French fleet in the Mediterranean; and about the same time the not less celebrated Turenne met his death from a cannon-ball in the midst of his triumphs in Germany.  This year was doubly occupied in a negotiation for peace and an active prosecution of the war.  Louis, at the head of his army, took several towns in Belgium:  William was unsuccessful in an attempt on Maestricht.  About the beginning of winter, the plenipotentiaries of the several belligerents assembled at Nimeguen, where the congress for peace was held.  The Hollanders, loaded with debts and taxes, and seeing the weakness and slowness of their allies, the Spaniards and Germans, prognosticated nothing but misfortunes.  Their commerce languished; while that of England, now neutral amid all these quarrels, flourished extremely.  The Prince of Orange, however, ambitious of glory, urged another campaign; and it commenced accordingly.  In the middle of February, Louis carried Valenciennes by storm, and laid siege to St. Omer and Cambray.  William, though full of activity, courage, and skill, was, nevertheless, almost always unsuccessful in the field, and never more so than in this campaign.  Several towns fell almost in his sight; and he was completely defeated in the great battle of Mount Cassel by the duke of Orleans and Marshal Luxemburg.  But the period for another peace was now approaching.  Louis offered fair terms for the acceptance of the United Provinces at the congress of Nimeguen, April, 1678, as he now considered his chief enemies Spain and the empire, who had at first only entered into the war as auxiliaries.  He was, no doubt, principally impelled in his measures by the marriage of the Prince of Orange with the lady Mary, eldest daughter of the duke of York, and heir presumptive to the English crown, which took place on the 23d of October, to the great joy of both the Dutch and English nations.  Charles was at this moment the arbiter of the peace of Europe; and though several fluctuations took place in his policy in the course of a few months, as the urgent wishes of the parliament and the large presents of Louis differently actuated him, still the wiser and more just course prevailed, and he finally decided the balance by vigorously declaring his resolution for peace; and the treaty was consequently signed at Nimeguen, on the 10th of August, 1678.  The Prince of Orange, from private motives of spleen, or a most unjustifiable desire for fighting, took the extraordinary measure of attacking the French troops under Luxemburg, near Mons, on the very day after the signing of this treaty.  He must have known it, even though it were not officially notified to him; and he certainly had to answer for all the blood so wantonly spilled in the sharp though undecisive action which ensued.  Spain, abandoned to her fate, was obliged to make the best terms she could; and on the 17th of September she also concluded a treaty with France, on conditions entirely favorable to the latter power.