In early September 1599, the Protestant-Dutch forces, supported by a German-mercenary army of 25,000 men led by Count Simon of Lippe advanced over Rees and laid siege to the town.Robert Watson / William Thomson p.41 On September 10, after a series of skirmishes near the town, the Spanish forces of Don Ramiro de Guzmán, Governor of Rees, supported by reinforcements sent by Don Francisco de Mendoza, lifted the enemy lines around Rees, causing a decisive defeat to the Protestant forces. The Spanish troops were outnumbered eight-to-one, but after two decisive assaults over the Protestant positions led by the two veteran captains Andrés de Ontoria and Andrés Ortiz, was sufficient to destroy the formations and defenses of the undisciplined and inexperienced German soldiers of the Protestant army. Count of Lippe's forces suffered about 2,000 to 2,500 casualties, hundreds of prisones, and a great part of the artillery and supplies were destroyed or captured. On the other hand, the casualties of the Spaniards were minimum. The offensive of the coalition forces of the Count of Lippe, Philip of Hohenlohe-Neuenstein, and the Count Ernst of Solms, despite the initial success in taking by surprise the fortress of Rheinberg on August 30, turned into a humiliation. Thereafter, the German army evaporated, and the siege ended with the withdrawal of the rest of the Protestant forces.
Aftermath
A few days after, the Spanish forces re-established control over the fortress of Rheinberg. By now, it had become clear that Spanish control of the Southern Netherlands was strong, and the threat of an invasion of the northern provinces was evident. In 1600, with the Army of Flanders now temporarily in disarray, Johan van Oldenbarnevelt spied a strategic opportunity to deal with the Archduke Albert. Prince Maurice advanced in direction of the port of Dunkirk that had grown into a hotbed of privateers that did much damage to Dutch and English shipping, and with the support of a large amphibious operation from Flushing, started his advance to the coast. The Spaniards, with the Army of Flanders ready, strengthened their positions along the coast, leading to the Battle of Nieuwpoort. Although the Dutch army led by Maurice of Nassau had driven a Spanish army from the field, a rare feat in the 16th century, the casualties on both sides were practically equal, and the battle achieved nothing. The Dutchlines of communication had already been stretched to the limit, and Maurice was forced to withdraw as well. Moreover, the great port of Dunkirk, which had been the principal objective of Maurice's campaign, lay out of reach and in Spanish hands. The Siege of Rees of 1599 was the last action of the campaign of Don Francisco de Mendoza, Admiral of Aragon, of 1598-99, also called the Spanish Winter of 1598-99.