The Battle of Mook

Dutch military operations developed successfully at sea, where the navy twice defeated the Spanish fleet. On land, however, the Spanish siege of Leiden continued. The basic aim of the campaign of 1574 outlined by prince William of Orange was to relieve Leiden. His brother Louis of Nassau, having recruited mercenaries in Germany, was to advance to Maastricht, and in case of failure there, to set off for Delft to join William's troops. Upon hearing of William's plans, the Spanish decided to prevent the Louis' troops from entering into Brabant, and from uniting his troops with those of William, who concentrated 6,000 infantrymen on the island of Bommel. To reach this goal, 8,000 horsemen and an appropriate number of infantrymen were hired in Germany. The command was commissioned to Sancho de Avila. In late February of 1574, in a heavy snowstorm, a mercenary army headed by Louis crossed the Rhine and headed for Maastricht. On the way to the Maas river, more than a thousand mercenaries deserted. The situation was further aggravated by the impossibility to cross the Maas due to the ice drift.

As a result of the battle, the Dutch lost a considerable part of their forces and the possibility to carry out any intensive military operations. Yet Avila was unable to make use of the great tactical success of his Spanish army due to a mutiny. The government had owed mercenaries their pay for three years, but still there was no sign of money.