In the first century BCE, very few people lived in what is now the province of South Holland in the Netherlands. Experts estimate that the population may have been 9.000 at most. The area was swampy and prone to flooding by the sea. The inhabitants were members of the tribe of the Cananefates, who lived of agriculture, livestock farming, fishing and hunting.
Everything changed when in about 12 BCE a new people appeared in the region: the Romans. The Roman presence – or, if you want: occupation – had a massive influence on life in this part of the Ancient World. Trade increased and objects from elsewhere in the Roman Empire found their way to the coast of Holland. The size of the population tripled to some 27.000 people around the year 150. Along the Roman border or limes – which was the Old Rhine since 47 CE – some 20 forts or castella were built, as well as dozens of smaller guard stations. These did not just serve defensive purposes, they were also the locations were trade was possible between the Romans and the Germanic tribes not under Roman rule. One of these castella was Praetorium Agrippinae. The settlement is mentioned on the well-known Peutinger Table (Tabula Peutingeriana), a map of which the original dates from the third or fourth century. There is a fair amount of certainty that this Praetorium Agrippinae corresponds with the modern town of Valkenburg in South Holland, which by the way should not be confused with the town of Valkenburg in Limburg.
Castellum and vicus
Extensive excavations conducted in the twentieth century have provided us with a lot of information about the castellum that was once located here in Valkenburg. Between 1941 and 1953, these excavations were led by the archaeologist Albert van Giffen (1884-1973). Later, in the 1970s and 1980s, more excavations were carried out southeast of the castellum, where the large vicus of Praetorium Agrippinae was once situated. The presence of a Roman army camp led to increased economic activity. It was in the vicus that the craftsmen – think of blacksmiths and saddle makers – and the traders settled. Veterans and the families of the soldiers also lived in the vicus. In fact, the Dutch word for a quarter or a neighbourhood is a ‘wijk’, which derives from the Latin word vicus.
The archaeological data available allow us to draw a few conclusions about Praetorium Agrippinae with a fair degree of certainty. The first castellum – of a total of seven – was founded in the year 39 or 40. There may have been a connection with the planned invasion of Britannia by the emperor Caligula (37-41). It is even possible that the emperor himself was present when the camp was founded. During excavations in Valkenburg, the lid of a wine barrel was found that was stamped with the words C CAE AUG GER, which is short for C[aius] [Julius] Cae[sar] Aug[ustus] Ger[manicus]. This was Caligula’s official name, his nickname ‘Caligula’ meaning something along the lines of ‘little army boots’. We can therefore conclude that wine from the imperial vineyards was consumed in Ancient Valkenburg. The lid with the stamp can certainly be considered a clue for the emperor’s personal presence, although it is not hard evidence. However, the name Praetorium Agrippinae doubtlessly has a connection with Caligula: the castellum is named after either his mother Vipsania Agrippina (ca. 14 BCE-33 CE) or his sister Julia Agrippina (15-59).
The first castellum was made of wood. It had five successors that were also – predominantly – made of wood. The seventh and last castellum dates from ca. 180 and was mostly constructed in stone. This fortification was part of a larger project that aimed to strengthen all forts on the Rhine border by providing them with stone walls, towers and gates. The project required large quantities of tuff, which were shipped to Praetorium Agrippinae from quarries in present-day Germany. During the so-called Crisis of the Third Century, which was roughly from 235 until 284, the castellum was abandoned, as were the other forts along the Rhine. However, the withdrawal of the troops did not mean that the Rhine was no longer considered the border of the Roman Empire. This would still be the case until shortly after 400. The Roman army simply switched to a different strategy. Defending a fixed border was replaced with defending the hinterland with more mobile units. The castellum of Praetorium Agrippinae must have been abandoned between 240 and 275. The vicus – in existence since about 70 CE – disappeared as well. What is interesting is that Praetorium Agrippinae was reused as a fortified granary for much for much of the fourth century.
The castellum covered an area that was 150 metres long and 170 metres wide. The camp was protected by an earthen rampart with a wooden palisade and by a triple moat. The seventh castellum was, as was already mentioned above, made of stone. Inside the camp were many buildings, for instance the barracks were the men lived, stables, storage rooms, a military headquarters and the residence of the commander and his family (the praetorium). The camp could accommodate a cohort of soldiers, so around 480 men. The actual number of inhabitants must have been smaller most of the time. More importantly, these men were formally not Roman soldiers, but auxiliaries (auxilia). Peoples that had been subjugated by the Romans were required to provide the Roman army with soldiers. After 25 years of loyal service, these men were granted Roman citizenship. The camp commander seems to have always been a prefect who was a Roman citizen. He was often a member of the equestrian order (equites) or an experienced centurion who had been given a promotion.
The first inhabitants of the original castellum were men of a so-called cohors equitata, a ‘mounted cohort’. This does not mean that all of them fought on horseback. On the contrary, a cohors equitata was a mixed cohort of infantry and cavalry, in this case of some 320 Gallic foot soldiers (two maniples) and 60 Gallic horsemen (two turmae or squadrons). The cohort was known as the Cohors III Gallorum equitata. Just a few years later, in about 42, the Gauls were relieved by half an ala of cavalry, some 250 horsemen. The presence of four times as many horsemen necessitated a remodelling of the camp. In the year 47, the castellum was destroyed by fire, presumably after an attack by Germanic troops. Its successor was subsequently lost during the so-called Batavian Rebellion of 69, which saw the local Cananefates join ranks with the rebel Batavi. This castellum was rebuilt as well and then remodelled. The new inhabitants were Thracians of the Cohors IV Thracum equitata. This was another mixed cohort of infantry and cavalry. Thracians may have been considered more reliable than local troops. Around the year 120, the military headquarters was rebuilt in stone and in about 175-180, the seventh version of the castellum was completed, almost completely constructed in stone.
People who visit Valkenburg today should realise that the course of the river Rhine is now different. The Old Rhine for instance crossed the modern Hoofdstraat (Main Street). In Antiquity, there must have been warehouses and other harbour buildings along the river. We know that for some time there was a small second fort here as well, which could accommodate some 80 men (a centuria), as well as a guard tower. Nowadays this is the location of the N206 provincial road. An artwork made in 2012 by Herman Bartelds, which can found along the Voorschoterweg along the modern Rhine, reminds us of Roman Valkenburg. The monument represents a Roman gate with three javelins or pila. Along the aforementioned provincial road is a second monument: a replica of a Roman road. The original road was presumably constructed shortly after 39, while a second one was made in 124. The road was about 4,5 metres wide. Along the monument are concrete cypresses and a copy of a Roman milestone that mentions the emperors Marcus Aurelius (161-180) and Lucius Verus (161-169).
If you want to know more about Praetorium Agrippinae, you can visit the local Torenmuseum. It is housed in the tower of the Protestant Church on the Castellumplein. Please beware that the museum is only open on Saturdays from 13:30 until 16:30.
This post was mostly based on information provided by the Torenmuseum.
 The local Torenmuseum has a dish with the inscription TVRMA IVLI, ‘squadron of Julius’.
 The Torenmuseum should be in possession of a tile with the text CHOIIIITR (Fourth Cohort of Thracians), but it seems to have been mislaid: it was nowhere to be found when I visited the museum.