In the Battle of Mookerheyde, Spanish forces defeated Dutch forces composed of German mercenaries on 14 April 1574 during the Eighty Years' War near the village Mook and the river Meuse not far from Nijmegen in Gelderland. Two leaders of the Dutch forces, brothers of William the Silent, were killed: Louis of Nassau and Henry of Nassau-Dillenburg.
During the winter of 1573/74, Louis and Henry of Nassau raised a mercenary army in Germany of 6500 infantry and 3000 cavalry. They proceeded towards Maastricht to rendezvous with their elder brother William the Silent, Prince of Orange, who led 6000 Dutchmen. They planned to march their combined forces toward Leiden, which was under siege by a large Spanish force since October 1573.
The strength of Count Louis' forces diminished en route. More than a thousand men deserted and seven hundred were killed by the Spanish in a night attack. The remaining troops were mutinous because the Dutch had been unable to pay them. Louis crossed the Meuse with only 5,500 infantry and 2,600 cavalry.