The town of Liège, which lies on the river Meuse, was in medieval times the capital of a huge province ruled by a Prince-Bishop, who was subject to the Holy Roman Emporer. It stood on the north bank of the river at the foot of a steep hill.
When the first fortifications were built around the town at the end of the 10th century, they mainly enclosed the lower town next to the river, although the circuit did extend up the hill to the west. This left the town dominated by the heights to the north, something which was rectified in the 13th century when the town had outgrown the original walls. A new circuit of defences was built, this time taking in the heights to the north as well as two large islands in the river that the town had spread onto.
It was onto this cicuit of walls that the first artillery defences were imposed in the mid-16th century. These consisted of 3 bastions'jutting out from the medieval wall on the north side of the town.
Although the Prince-Bishopric of Liège was surrounded by the Netherlands, it was not among the 17 provinces and so it was largely unaffected by the wars of the Dutch Revolt'in the late 16th and early 17th centuries, but it did suffer from a civil war in the first half of the 17th century.
In 1650 Prince-Bishop Maximilien-Henri de Bavière put an end to the civil war and began the construction of an earthwork citadel'on the heights on the north side of Liège.
This citadel dominated both the land to the north and the town to the south. It incorporated the 16th century Bastion de Sainte-Walburge, which had been built onto the medieval wall. There was an irregular bastion to the east and four more bastions facing the town.
The immense strategic value of the citadel to control and protect Liège was immediately evident. As a result 13 years later in 1663 work began to construct a new stone citadel to replace the decaying earthworks. This new citadel was completed in 1671.
The new citadel was more compact than the old citadel and did not extend so far west (part of the western defences of the first citadel were left in place to provide an extra layer of defence towards the town). There were 5 bastions and a demi-lune'protecting the entrance.
The trace on the north side was slightly imperfect due to the fact that it followed the course of the old city walls (and the old citadel) at this point. This suggests that the focus was on the defences facing the town and that the main purpose of the citadel was initially to control the inhabitants of Liège.
All this was to change in the 1670s when the French king Louis XIV'declared war on the Dutch and sought to march through Liège's territory in order to attack them. In 1672 the Prince-Bishop allowed them to do this, but when he wavered in his commitment to Louis and considered concluding an alliance with Spain in 1675, French troops were sent to occupy the town of Liège to secure the route to France. In 1676 they slighted the citadel, mining its ramparts.
This act was designed to prevent the citadel from being used by an enemy and to prevent the fortress of Liège from becoming an obstacle for France in the future. In 1684, in the face of continued French attacks against the Spanish Netherlands, the Prince-Bishop ordered that the citadel be rebuilt (to the same plan).
A treaty was signed between Liège and France in 1689 stipulating the demolition of the citadel in return for the neutrality of the Prince-Bishopric. However, it is unlikely that this was carried out since later in the year Liège joined the Allies against France.
In September of 1689, with Liège now part of the Grand Alliance against France, Dutch engineers arrived to assess the fortifications. They identified a weakness to the east, where the convent of La Chartreuse was situated on high ground overlooking the town.
Concerned that these heights would make it easy for an enemy to bombard the town, they began building the Fort de la Chartreuse to defend the area. However, the construction work was only undertaken slowly and the fort was practically useless when the French arrived in 1691.
Boufflers' army had been sent by Louis XIV to punish the town for reneging on its promise of neutrality 2 years earlier. The French bombarded the town from the east, having overcome the incomplete Fort de la Chartreuse without difficulty.
After this disastrous failure, the Allies sent the engineer Menno van Coehoorn'to Liège to put the town in a state of defence in case the French should return. Coehoorn rebuilt the Fort de la Chartreuse and ordered the construction of entrenchments to the north of the town.
Coehoorn's Fort de la Chartreuse probably took the same form as the first fort, consisting of a front of two bastions supported by two demi-bastions'at the rear. There were 3 demi-lunes, a covered way'and various advance entrenchments.
On the high ground to the north of the town, far in advance of the walls and the citadel, Coehoorn built a long line of entrenchments. These fortifications were designed to be defended by a force of light troops that could easily move to reinforce a threatened section.
This work vastly improved the strength of Liège as a fortress, although the citadel, which had fallen into decay, was given little attention. After the Treaty of Rijswijk'put an end to the war, the nuns of La Chartreuse complained that the fort had been built on their land. In 1700 they were given permission to demolish it.
This turned out to have been an unwise move, since war broke out again in 1701, but this time Liège took the side of the French, perhaps still fearful of them after the bombardment 10 years earlier. French engineers were soon in the town, restoring the citadel and the Fort de la Chartreuse.
In 1702, after reading reports of the dilapidated state of the defences, the French engineer Vauban'came to Liège. His primary goal was to persuade the Prince-Bishop to finance the work on the fortifications, but since he was in the town for 3 months, it is likely that he at least surveyed the works.
The restoration work was still incomplete when the Allies attacked in 1702. After a lightning advance down the Meuse, taking Venlo, Stevensweert and Roermond, they laid siege to Liège in October. Coehoorn, who had been strengthening the defences a few years previously, was now directing the attacks against them. The citadel, which was attacked first, fell relatively quickly due to the poor condition of the walls and the Fort de la Chartreuse surrendered a few days later.
In 1705 the French returned and invested Liège, but they retreated when Marlborough'moved north with his army. Following this, the Dutch decided to strengthen the town's defences again in case of another French attack.
This work took the form of advance works to reinforce the citadel. There were 3 lunettes'to the north and one facing west, inside the city walls. Another small redoubt'faced south, towards the town. The town walls remained more or less as they were in medieval times.
However, these additions were short-lived, since the Treaty of Rastatt demanded their demolition along with other parts of the fortifications. The bastions of the citadel that faced away from the town were removed, as were the new lunettes and the Fort de la Chartreuse.
But this demolition was by no means the end of Liège as a fortress. A hundred years later, after the Napoleonic Wars it was decided that the Meuse fortresses were needed again. In 1817 the citadel was re-fortified, with new detached bastions facing away from the town.
A new Fort de la Chartreuse was also built, slightly to the south of the site of the original fort, but performing the same function. The new fort was considerably larger, with 5 bastions, one of which was a redoubt in its own right.
In the 1880s, Liège, along with Antwerp and Namur, was transformed into a modern fortress. A total of 12 outlying forts were built surrounding the town, designed to prevent an enemy coming close enough to bombard it.
It was these forts enabled the Belgian army to delay the German advance at Liège in 1914, giving the Allies valuable time to assemble their forces in northern France.
The citadel of Liège survived intact until 1974, when a new hospital was built on the site, resulting in the demolition (again) of most of the defences facing away from the town. In the south the ditch was filled in but the walls were not destroyed.
Today, two and a half bastions and two demi-lunes survive on the southern side of the citadel, as well as one of the 19th century detached bastions on the north side. The ramparts now surround a modern hospital and can be visited freely by the public. The climb up the hill is worth it just for the views over the town from the south side of the citadel.
The medieval walls were mostly demolished in the 19th century as the town expanded, but fragments remain, now crowded (and sometimes built onto) by houses. Notably the Tour Moxhon and the Tour des Bégards have survived on the east side of town.
The early 19th century Fort de la Chartreuse still exists, although it is fenced off and cannot be visited by the public at present. The late 19th century forts that were the scene of the Battle of Liège in 1914 also survive and some can be visited.
Lastly, there are some remains of the wall running south from the citadel down the hill to the river (see left). There are three stations in Liège, but Liège Palais is the best one to get off at, since the citadel and the fragments of medieval walls are all within a short walk from it.
The Fort de la Chartreuse is farther south, across the river, but it is not too far to walk. The outlying forts however, would probably require some form of transport to get to.