Capture of Maastricht The siege of Maastricht was fought between June 9 , 1632 to August 22 , 1632 where the Dutch commander Frederick Henry , Prince of Orange eventually captured the city from Spanish forces . Background . Following upon his success of 1629 , the capture of ' s - Hertogenbosch , the Dutch commander Frederick Henry , Prince of Orange marched up the river Maas ( Meuse ) in 1632 . The aim of the campaign was an ambitious one - the capture of the strong fortress of Maastricht , which was deep in Spanish - held territory . As Prince Henry marched south , the fortified places of Venlo and Roermond capitulated with very little resistance thanks to the efforts of the Stadtholder of Upper Gelderland , Van der Bergh , who was sympathetic to the Dutch cause . In 1632 Maastricht was ringed by tall medieval walls with a large number of towers . A few earthen bastions and demi - lunes had been constructed to strengthen the defences against artillery . A flooded ditch fed by water from the river protected the low - lying parts of the defences . The town lies on both sides of the river Maas , which is particularly wide at Maastricht , so any attacker would have his forces split into two by the river . The garrison was strong , loyal to Spain and determined to resist the Dutch army . In addition to all this , there was a strong chance of a relief army being sent to Maastricht to raise the siege . The Siege . Frederick Henry arrived before Maastricht on June 10 with 17 , 000 infantry and 4 , 000 cavalry . This included some veteran English and French troops , who were to play a significant role in the siege . He at once began to dig lines of circumvallation and contravallation . These were earthwork fortifications that ran all the way round the town and were built to protect the besiegers ' camps against sorties made by the garrison or attacks from a force outside the town . There were various forts and redoubts along these lines protecting the high ground or vulnerable sections . Where the lines met the river above and below the town pontoon bridges were constructed , allowing the besiegers to transfer troops and material from one side of the river to the other . The strength of these lines was to prove critical to the outcome of the siege . Two approach trenches were made on the town , one by the English troops and the other by the French . The English and French approaches drove towards sections of the defences to the north and south respectively of the western corner of the town . The French approach targeted a section of medieval walls that was inadequately flanked by the works either side of it and the English approach aimed just to the south of a demi - lune in front of the walls . 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 July 2 with 18 , 000 infantry and 6 , 000 cavalry , but though they outnumbered Frederick Henry ' s army , they was unwilling to attack the Dutch lines on account of their strength . By the beginning of August Don Gonzalo de Córdoba was reinforced by the Imperial commander Pappenheim , who brought 12 , 000 infantry and 4 , 000 cavalry . He resolved to attack the Dutch lines and force them to raise the siege . In a two - pronged attack , Don Gonzalo made a show of force on one side of the river and Pappenheim attacked the lines on the other side . This plan was well - conceived but in the end the strength of Frederick Henry ' s lines of contravallation and the superior morale of his troops ( who were encouraged by his presence during the fighting ) decided the day . Pappenheim was forced back with the loss of 1500 men . One of the casualties on the Dutch side was Robert de Vere , 19th Earl of Oxford . Having failed to raise the siege by force of arms , Don Gonzalez and Pappenheim decided to cut the Dutch supply lines and so starve them out of their strong position . However , the besiegers had sufficient supplies in their camps for another two months , so Frederick Henry simply ignored the relief forces ' actions and pressed on with the siege . The attackers were faced with a determined resistance from the garrison who made many sorties , particularly against the English approach , but in the end both the approaches reached the ditch . It was decided to mine the walls to form a breach and to this end two tunnels were dug beneath the ditch . A mine was detonated in one of them underneath the walls and a forlorn hope assaulted the breach on the night of August 21 . This assault succeeded in gaining a lodgement in the walls and the garrison capitulated the following morning , fearing that the town would be sacked if the attackers broke in . Aftermath . The garrison marched out with the honours of war on August 23 and Pappenheim and Don Gonzalo , who were still camped nearby but were running low on supplies , withdrew . Frederick Henry ' s feat in capturing Maastricht dismayed the Spanish , who made negotiations for peace , but their resolve was stiffened a few months later by the death of the Swedish Protestant hero Gustavus Adolphus at the Battle of Lützen on November 16 . Nevertheless , the capture of Maastricht was an important victory for the Dutch Republic . While Venlo and Roermond were lost to the Spaniards in 1637 , Maastricht remained in Dutch hands , even though sovereignty over the condominium was to be shared with the prince - bishops of Liège .