 This siege took place long before the days of parallel trenches, so the works consisted of eccentric zig-zag trenches and self-contained batteries that formed strong points.In response to the investment of Maastricht, Isabella (the Governess of the Spanish Netherlands) recalled her troops from the Palatinate and sent Don Gonzalo Fernández and the Marquis of Santa Cruz to relieve the town.The Spanish arrived near Maastricht on 2 July with 18,000 infantry and 6,000 cavalry, but though they outnumbered Frederick Henry's army, they were unwilling to attack the Dutch lines on account of their strength.