The siege of Maastricht took place from 13 to 30 June 1673 during the 1672 to 1678 Franco-Dutch War. A French army captured the Dutch fortress of Maastricht, which occupied a key strategic position on the Meuse river and was their main objective for 1673.
The siege was conducted by Vauban and is thought to be the first use of a technique known as the "siege parallel", a concept that remained in use until the mid-20th century.
Unsuccessfully besieged by the Dutch in 1676, Maastricht was eventually returned under the terms of the 1678 Treaty of Nijmegen.
Background
In the 1667–1668 War of Devolution, France captured parts of the Spanish Netherlands and the entire Franche-Comté but was forced to relinquish the bulk of these gains in the Treaty of Aix-la-Chapelle (1668) with the Triple Alliance of the Dutch Republic, England and Sweden. Before making another attempt to gain territory in the north, Louis XIV strengthened his diplomatic position by paying Sweden to remain neutral, while England agreed an alliance against the Dutch in the 1670 Secret Treaty of Dover.
When the French invaded the Dutch Republic in May 1672, they initially seemed to have achieved an overwhelming victory, capturing the major fortresses of Nijmegen and Fort Crèvecœur near 's-Hertogenbosch and occupying Utrecht without a fight. However, by late July, the Dutch Water Line had stabilised the front lines, while concern at French gains brought the Dutch support from Brandenburg-Prussia, Emperor Leopold and Charles II of Spain. Forced to divide his forces, in August Louis sent Turenne and 50,000 troops to the Rhineland.
Maastricht is located on the extreme eastern edge of the Flanders region, a compact area 160 kilometres wide, the highest point only 100 metres above sea level, and dominated by canals and rivers. Until the advent of railways in the 19th century, goods and supplies were primarily transported by water and campaigns fought over the control of rivers such as the Lys, Sambre and Meuse. Along with Sedan, Namur and Liège, Maastricht is one of a series of strategic fortress cities that control the Meuse valley and bridges over the river. Captured in 1632 from the Habsburgs by Dutch stadtholder Frederick Henry of Orange, its fortifications were considerably expanded until 1645.
Its location on both banks of the Meuse made the town extremely important and it was one of the few garrisoned in peacetime. Dutch engineer Menno van Coehoorn began his career there in 1657, as a young Lieutenant in his father's company. Prior to the 1672 invasion, the French prepared forward supply bases in the Bishopric of Liège and the Dutch responded by concentrating 11,000 mercenaries in Maastricht. They hoped that a prolonged siege would gain them sufficient time to prepare the six Rhine fortresses defending the eastern border of the Republic.
The French reached Maastricht on 17 May 1672. Louis wanted to capture the fortress first, but on advice of Turenne bypassed the main defences and only with ten thousand men occupied the satellites of Tongeren, Maaseik, and Valkenburg. This allowed him to overrun the Rhine fortresses and the entire Republic seemed on the verge of collapse before the Dutch managed to stabilise their position in August. The retention of Maastricht now allowed them to threaten the extended French supply lines. In November 1672, William III of Orange used it as a base for an attack on Charleroi, the French-held city at the start of their supply route, taking most of the garrison with him.
As a result, capturing Maastricht was made the primary objective for the French 1673 campaign. The army was accompanied by Louis XIV, for whom sieges were seen as a propaganda tool. While Louis assembled his forces around Kortrijk, another French army was concentrated in the west for a feint attack against Bruges, to prevent Spanish troops from further reinforcing Maastricht. While officially neutral, the Spanish Netherlands provided the Dutch with financial and diplomatic support, since their occupation was Louis' ultimate aim. The French opened the siege on 13 June.
Advances in siege tactics
thumb|The siege parallel: three parallel trenches, linked by communication lines. The first is out of range of defensive fire, the third brings the attacking troops as close to the assault point as possible, while redoubts protect the ends of each.
Maastricht was the first siege where the famous French engineer Sébastien Le Prestre de Vauban directed operations, rather than being a technical advisor. He was not a military commander and according to the custom of the time, subordinate to the senior officer present, in this case Louis XIV. Louis had forbidden his generals de Condé or Turenne to be present at the siege to prevent them from sharing in the glory. The King regularly visited the trenches, exposing himself to enemy fire and was closely followed by painters and poets who had to immortalise his exploits for posterity, as well as the court historian Paul Pellisson.
thumb|left|300px|The circumvallation.
Although commonly remembered for the fortifications he built, Vauban's greatest innovations were in the field of offensive operations. Some years before the capture of Maastricht he had expressed his thoughts on siege warfare in a manuscript, that after his death, in 1740, was published under the title Mémoire pour servir d’instruction dans la conduite des sièges et dans la défense des places. This has provided modern researchers with some insights about the general principles Vauban probably applied. The 'siege parallel' had been in development since the mid-16th century but Maastricht saw him bring the idea to practical fulfilment. Three parallel trenches were dug in front of the walls, connecting the perpendicular assault trenches, the earth thus excavated being used to create embankments screening the attackers from defensive fire, while bringing them as close to the assault point as possible (see Diagram). The transverse parallels allowed a much larger number of troops to participate simultaneously in an assault to overwhelm the defenders, while avoiding choking points that often had led to costly failures. Artillery was moved into the trenches, allowing them to target the base of the walls at close range, with the defenders unable to depress their own guns enough to counter this. Once a breach had been made, it was then stormed. This remained the standard for offensive operations until the early 20th century.
Vauban was unusually sympathetic to the impact of war on the poor, on one occasion requesting compensation be paid a man with eight children whose land was taken to build one of his forts. However, his siege works required large numbers of unpaid workers, with severe punishments for those who tried to evade service. 20,000 local farmers were conscripted to dig his trenches at Maastricht.
Troop strengths
thumb|right|350px|1865 engraving of a [[ravelin at Maastricht, similar to that captured by French troops on 24 June 1673.]]
The Treaty of Dover included an agreement by Charles II to supply a brigade of 6,000 English and Scottish troops for the French army. It also contained secret provisions, not revealed until 1771, one being the payment to Charles of £230,000 per year for these troops. While Charles was anxious to ensure Louis felt he was getting value for money, there were considerable doubts as to the brigade's reliability if asked to fight the Protestant Dutch on behalf of the Catholic French. As a result, it formed part of Turenne's force in the Rhineland but several officers, including the Duke of Monmouth and John Churchill, future Duke of Marlborough were present at Maastricht as volunteers and given prominent positions by Louis to gratify his English ally. The attacking forces numbered about forty thousand men. Louis had tried to dissuade Monmouth from participating, fearing that his death might deteriorate relations with England, but ultimately the king felt obliged to give his permission though providing him with a bulletproof armour, which indeed might have saved his life. Vauban had ordered that the secondary attacks had to be only feints, but to his disgust Monmouth attempted to scale the hornwork and was beaten off with heavy losses, over a hundred casualties. At the first contre-escarpe, an artificial escarpment offering the defenders a forward covered transverse communication line, and the Groene Halve Maen, the French too suffered many losses, especially among their officers. The lunette was taken, quickly recaptured by a counterattack and then taken again. In the late evening, French engineers connected the lunette to the third parallel via a provisional communication trench. while passing through a breach in the first contre-escarpe palisade. Of the three hundred musketeers deployed, over eighty had been killed and over fifty severely wounded. In their honour, a later ravelin erected on this location was to be called the demilune des mousquetaires. In this critical phase of the battle, Vauban lost his confidence. It had been assumed that the morale of the garrison was low but it now proved to be much more aggressive than expected. Also he worried about the possible extent of the tunnelling. He wrote to François-Michel le Tellier, Marquis de Louvois, the French minister of war, that if the Dutch managed to recapture the lunette for a third time, it was a distinct possibility that the siege would have to be lifted. At first the attackers had only a tenuous hold on the lunette and it would take them over five hours to bring up reinforcements. Another sortie would not materialise however, the population beginning to fill the gate with manure. There would be no plundering. Maastricht was a condominium of the Duchy of Brabant, the rights of which had been subsumed by the Dutch Republic and Liège. The bishop of Liège, Maximilian Henry of Bavaria, was Louis's formal ally in the war. Also, the French king claimed to be the rightful Duke of Brabant already, as the title would be part of the dowry of his wife. In any case, he intended the city to be a permanent French possession. Immediately after the surrender two French regiments occupied the Duitse Poort in the east Wijck suburb and, in the west, the Brussels Gate through which Louis would make his triumphal entry. Grave was recaptured by the Dutch in 1674.
The alliance between England and Catholic France had been unpopular from the start and although the real terms of the Treaty of Dover remained secret, many suspected them. In early 1674, Denmark joined the Alliance, while England and the Dutch made peace in the Treaty of Westminster. William III tried to recapture Maastricht in 1676 but failed, the French having greatly improved the fortifications according to a plan drawn by Vauban. After much controversy among historians, the present consensus is that this model was discarded relatively early and is not identical to the extant Maastricht maquette in the Paris Musée de l'Armée which shows the situation in the middle of the eighteenth century. On 16 September 1673, de Louvois had written that Louis would sooner give up Paris or Versailles than ever return Maastricht, but the city was nevertheless returned to the Dutch when the Treaty of Nijmegen ended the war in 1678. The French used the city as a bargaining chip to seduce the Dutch to cease supporting the Spanish war aims. They had promised that after a victory, the city would be ceded to the Spanish Netherlands, but refused when peace had been signed, claiming that otherwise the treaty conditions would be violated.
The siege was the subject of a set of paintings by Charles Le Brun on the ceiling of the Hall of Mirrors in Versailles. Adam Frans van der Meulen also dedicated a series of paintings to the event. Louis had the Porte Saint-Denis redesigned to commemorate this siege also, a plaque dedicating it LUDOVICO MAGNO, QUOD TRAJECTUM AD MOSAM - XIII. DIEBUS CEPIT, "to Louis the Great, for capturing Maastricht in thirteen days".