Castrum to Castle: Classical to Medieval Fortifications in the Lands of the Western Roman Empire

Chapter One

The Roman Era

From Fortified Camp to Fortified Frontier

In the fourth century

BC

, Ancient Rome, like most other city-states, was protected by walls to ward off its enemies. Built early in that century, the Servian Walls, built of tufa – a soft limestone common in Italy – surrounded the City on Seven Hills. Like those of other cities, they included a ditch on the outside and probably an earthen backing that provided additional support for the masonry and a wall walk. Late in the late third century

BC

, these walls warded off Hannibal’s army during the Second Punic War. However, before the war, the Romans had not been greatly concerned in building fortifications since they had focused on expansion. Their main military weapon for offense and defence became well-built roads that allowed their legions to move quickly to any threatened spot and prepare for offensive operations, react to an invasion and dominate land trade. During the Civil War in the first century

BC

, the old walls of Rome were reinforced and modernized. According to nineteenth-century historian Theodor Mommsen, after Julius Caesar conquered Gaul the Romans adopted a policy of ‘aggressive defence’, which was implemented mainly under Caesar’s successor, Augustus. It consisted of maintaining positions along the frontier, which incorporated rivers and man-made ramparts. In addition, the Romans founded colonies in the conquered territories and formed alliances with the neighbouring tribes, which served as buffers against other tribes located beyond them. Sometimes, these colonies were established in or near fortifications built by the Roman legions. This policy allowed the Romans time to ‘civilize’ and acculturate the conquered territories.

Well before the first century

AD

, the Romans had become skilled builders and used field fortifications like no others before them. Their work, however, was not totally original for they borrowed their construction methods from the Greeks and other peoples of the Hellenistic Age¹ and improved upon them. When a Roman legion advanced into hostile territory, each night it stopped it built a fortified encampment, which was a virtual fort or even a fortress considering the number of men (5,000 or more) it held. During each day the unit remained at the same location, the troops continued to strengthen the position with turf and timber² until it became a veritable ‘legionary fortress’ in our modern terminology. This, however, did not happen very often until the first century

AD

.

The Roman Empire occupied most of Western Europe, including modern day France, Spain, Portugal and England before the end of the first century

AD

. Its tentacles reached into what are now the Low Countries, parts of Germany along the Rhine and much of Britain where border walls were built after the first century

AD

. At the same time, Rome concentrated on holding the Rhine and the area between the Rhine and Danube rivers along the frontier with the hostile Germanic tribes. The Danube formed a frontier for the Roman Empire in Eastern Europe. In all cases, the Romans depended on fortifications to protect the territories they held. The defences from the Netherlands along the Rhine to Switzerland eventually formed the boundary between Germanic and Latinized Europe not only during the Roman Era, but well into the Middle Ages. This region was first fortified with the Roman limes and eventually became the home of the French Maginot Line and German West Wall, becoming the most heavily fortified area in Europe. Due to the development of feudalism, which resulted in a different type of warfare, this area had no defensive lines during the medieval period.

Map of the Roman Limes. Modified by Kaufmann from the 1911 atlas by Shepard. Photos of reconstructed watchtowers: wooden tower near Utrecht by Niels Bosboom, and stone tower near Kastell Zugmantel by Oliver Abels. (From Wikimedia)

During the first two centuries

AD

, especially after the destruction of three legions of Emperor Augustus in the Teutoburg Forest (in modern day Germany) in

AD

9, the Romans launched another campaign against the barbarians. It ended in

AD

17 when Emperor Tiberius ordered his legions to withdraw behind the Rhine in Lower Germania. Next, Rome tried to consolidate its borders by establishing a fixed frontier and fortifying it. The Romans referred to the frontier as the ‘limes’ or limits. As these borders were fortified, the term ‘limes’ eventually came to mean fortified line.³ Mommsen discovered that the frontier was marked by an Imperial frontier road and an adjacent ditch that resulted from excavating the soil to form an agger or road embankment or rampart.⁴ Roman colonies sprouted around the forts built along the Rhine and Danube barriers. An actual defensive line connected the two rivers in the region known as Raetia.⁵ The legions struck at the barbarians on the other side of the frontier from their fortified camp whenever they appeared to threaten the empire’s security. The section of the limes along the Rhine and the Danube relied mostly on water barriers. The Rhine positions spanned a total length of about 568km (353 miles) and over time it came to include over fifty forts and hundreds of watchtowers.

Defence of the Lower Rhine: The Batavian Revolt of

AD

69–70

The death of Nero in

AD

68 triggered a far-reaching civil war. As a result,

AD

69 became the ‘Year of Four Emperors’, the third of whom was Vitellius. The seven legions in upper and lower Germania proclaimed him emperor in January 69. That same month, the Praetorian Guard in Rome eliminated Galba and installed Otho as emperor. Vitellius marched on Rome and defeated Otho’s army near Cremona at the Battle of Bedriacum in mid-April. Otho committed suicide. In July, with Vitellius still in power, the eastern legions proclaimed Vespasian as emperor during the Jewish War. In October 69, Vespasian’s troops defeated Vitellius’ legions at the Second Battle of Bedriacum in late December, fought their way into Rome and killed Vitellius. Vespasian did not reach Rome from Egypt until the summer of 70.

The civil war encouraged Julius Civilis, a Batavian auxiliary commander, to lead a revolt in Batavia. In addition to locals, he recruited five cohorts (about 480 men each) of Batavians at Mogontiacum (Mainz). En route, he notified the commander of I Legion at Bonna (Bonn) that he only wanted to pass through without fighting. However, 3,000 legionaries and some auxiliaries came out of the fortress to stop him. Eventually, the Romans broke and retreated to the ditch and gates of the fortress where they took heavy losses. The defeated I Legion ‘Germanica’ at Bonna surrendered and the fortress was destroyed. The Batavians moved on, avoiding Cologne.

In the autumn of

AD

69, the Batavians had the advantage, according to Tacitus. Three legions deserted and joined the rebels. Civilis defeated the Roman V and XV Legions near Noviomagus (Nijmegen). The defeated legionaries retreated to the fortress of Vetera (Xanten). According to Tacitus, the remnants of this force, which included about 5,000 men and a large number of camp followers, took refuge in the fortress, which was well stocked with everything except food. Further up the Rhine another earth-and-timber fortress at Novaesium (Neuss), was destroyed by the rebels and the remnant of its XVI Legion made their way to Vetera. When the revolt had begun in the autumn of

AD

69, a coastal tribe supporting the Batavians had launched a surprise attack on the Valkenburg fort, which stood near the mouth of the Rhine protected by the river and was surrounded by three water ditches and destroyed it. Smaller Roman forts in the region had been evacuated and burned while a naval flotilla was lost to the rebels. The Batavians outnumbered the Roman forces including those at the fortress of Mogontiacum (Mainz). The only remaining major force was the XXI Legion in Upper Germania at the fortresses of Vindonissa (Windisch).

The Roman commanders at Vetera had strengthened the ramparts and walls and removed the nearby buildings of a small town. They ordered the legionaries to loot the area to supplement their meagre food supply. The fortress, observed Tacitus, stood partially on the gentle slope of a hill and partially on level ground, a situation that was not ideal for defence.

The rebels opened their attack on the fortress with a hail of missiles from a distance, failing to cause any damage while the defenders pelted them with stones, inflicting casualties. The Batavians next ‘charged with a wild shout and surged up to the rampart, some using scaling ladders, others climbing over their comrades who formed a tortoise. No sooner did some of them scale the wall, however, than the besieged repelled them with swords and shields and buried them under a cloud of stakes and javelins.’

The Batavians resorted to siege engines, with which they were quite unfamiliar. Deserters and prisoners had to show them how to build a sort of bridge or platform of timber on which they fitted wheels to roll it forward. Some of the men stood on this platform and fought as though they stood on a mound, while others, concealed inside, tried to undermine the walls. The defenders, however, destroyed this rude contraption with stones hurled from catapults. Next, the Batavians readied hurdles and mantlets, but the besieged set them ablaze with flaming spears shot from engines and even targeted the assailants themselves with fire-darts.⁶

These setbacks did not end Civilis’ efforts to take the fortress by storm. According to Tacitus, his men clamoured for a fight and fought with ‘blind fury’, so he sent them once again to destroy the rampart. They were beaten back again, suffering losses that mattered little because there were so numerous. During the night, they lit huge fires around the ramparts and sat there drinking wine. They hurled their missiles against the defenders who riposted with great effect. Since the rebels’ bright ornaments reflected in the fire making them easy targets, Civilis ordered his men to douse the fires. The Romans stayed on watch the whole night. At the merest sound of rebels climbing the walls or setting a scaling ladder against it, they stood ready to push them back from the battlements with their shields and swords and shower them with javelins. After sunrise, the Batavians appeared with a two-storey wooden tower, which they proceeded to haul up to one of the gates. The legionaries, wrote Tacitus, ‘by using strong poles and hurling wooden beams, soon battered it to pieces, with great loss of life’. The weapon that terrified the rebels the most, he observed, was a crane with a movable arm that hung above the enemy below the walls. This arm suddenly dropped and snatched one or more warriors, swung around and tossed them into the middle of the camp.

At this point, Civilis concluded that the fortress had limited provisions and decided to wait the defenders out by continuing the siege. His overconfident German troops, he concluded, lacked the means and skill to succeed in this type of warfare. He launched a surprise attack against the Romans on 1 December at Krefeld and lost in a Pyrrhic victory for the Romans. At this point, he gave up the siege of Vetera and advanced on Mogontiacum. The Romans sent a relief expedition to Vetera, resupplied the fort and strengthened it defences. However, since Mogontiacum was threatened, the Roman force withdrew taking 1,000 of Vetera’s defenders with it. As the Romans moved to protect the Mogontiacum fortress, Civilis broke off his siege there and returned to besiege Vetera. In March

AD

70, their supplies exhausted, the Romans surrendered Vetera on condition their two legions would be allowed retreat behind Roman lines. The rebels broke their pledge and attacked and destroyed the two legions shortly after they left their fort, despite Civilis’ efforts to stop them.

Vespasian’s response was to send eight legions to put down the rebellion. A treaty was signed in

AD

70. A legion was sent to build a new fortress at Noviomagus in order to strengthen control of the area. Other legions replaced the destroyed fortresses at Bonna, Vetera and Novaesium with stone ones. The fortress at Novaesium remained in service for only a few decades and was replaced with a fort. The Roman defences along the fortified limes of the first century and even the second century were strong despite the events of the Batavian Revolt.

Roman expansion ended early in the second century

AD

when Emperor Trajan conquered Dacia. He also completed and strengthened the Limes Germanicus begun by Augustus. Lewis Sergeant, another nineteenth-century historian, wrote,

Starting on the Main and nearly bisecting the great curve of that river already mentioned, it ran northwards, about half-way between the modern Frankfort and Karlstadt; then, taking a wide sweep over hill and valley and morass, amongst the sources of many northward and southward streams, climbing the crests of the Taunus and the northern limits of the Rheingau, it approached the Rhine opposite to Vosolvia (Ober-Wesel). Hence it ran parallel to the stream, across the Lahn, over against Confluentes (Coblenz), at the embouchure of the Mosella and past the modern Ehrenbreitstein, ending in what is now called the Westerwald, a little above the town of Bonn and the tributary Sieg.

The Limes ended at Rigomagus (Remagen) on the Rhine and thence, along the left bank, ran a line of Roman forts, the chief of which were Bonna (Bonn), Colonia Agrippina (Cologne), Durnomagus (Dormagen), Novæsium (Neuss), Gelduba (Gellep), Asciburgum (Asburg), Vetera Castra (Birten), Colonia Trajana, Burginatium (Schenkenschanz) and Noviomagus Batavorum (Nimeguen). From Remagen to Nimeguen is a distance of about 105 miles in a straight line. Near some of these towns there would be permanent Roman camps, whilst some of them were Roman colonies …⁷

In Britannia, Emperor Hadrian, Trajan’s successor, ordered the construction of the wall that bears his name across the island to keep the northern tribes at bay. Emperor Antoninus Pius, who succeeded Hadrian, advanced the position northward, creating a new wall that was later abandoned. These walls were different than those on the land frontiers of Europe.⁸

The Romans marked their limes with a vallum (a defensive wall or rampart),⁹ which may have been merely an earthen rampart that served as a boundary marker not always intended as a fortification. The fortified limes consisted of a vallum made of the materials from the excavation of the defensive ditch or fossa, usually V-shaped, in front of it. The work was done by Roman troops who often added a wooden palisade to the rampart. Wooden watchtowers, garrisoned by about eight men,¹⁰ served as signal stations between forts and were positioned at regular intervals on the frontier. Some had a surrounding wall and ditch.¹¹

Auxiliary forts and legion fortresses, often associated with a Roman colony, occupied key locations on or behind the limes. They usually stood on high ground or at river crossings and some blocked mountain passes. The size and shape of the fortifications varied, but they generally followed a standard pattern. The forts were smaller than a legionary fortress (see sidebar for terminology). They were built by Roman auxiliary units that usually consisted of non-Romans who were promised citizenship after about twenty-five years of service. The auxiliary units received assistance from engineer specialists from a nearby Roman legion. The shapes and components of both types of fortification were more or less standardized. They were usually square or rectangular, but some conformed to the terrain. Rounded corners were standard. All work was done by legionaries and auxiliary troops in the same way as the entrenched camps during a campaign. The auxiliary forts varied in size from large enough for selfsufficiency to smaller ones that had no headquarters and were probably detached from another position. The smaller positions usually had a single entrance and have been referred to as fortlets. Size also depended on the type of unit (infantry or cavalry) that occupied it, but in the centuries

AD

the units on the frontier included a cavalry element. Standard features for most forts were similar to those of a legionary fortress. They included barracks, whose number depended on the size and type of detachment it held, a residence for the commander and a centrally-located headquarters. Large forts usually included a granary and most had additional buildings. With few exceptions, the entrances of the fort were situated at or near the centre of each of its four sides. In the later part of the third century, under Diocletian, the number of entrances was reduced as was the size of forts, which were built with higher walls twice as thick as earlier works and no longer used earthen backing. These new forts were meant for smaller garrisons since before the end of the third century a large fort held housed a 500-man cohort and a legionary fortress, a legion of 5,000 to 6,000 men. This reduced size became standard to match the smaller size of the legions, which now numbered as few as 1,000 to 2,000 men. Auxiliary units were reduced to 25 per cent of their original strength. When they had to renovate older positions during this period, the troops rebuilt the walls to enclose a smaller area, but left the old surrounding fossa and added new ones between them and the new walls thus creating three to five ditches.

The Romans also fortified landing sites on the Rhine and Danube because the navy could resupply forts more efficiently by water than by road since ships had a larger cargo capacity than wagons. A fortification was often built on the enemy side of the river, opposite a fort or fortress, to protect the ships while they were unloading. It seems that most of these sites were built during the reign of Constantine and Valentinian.

Fortresses and Forts

One of the first features created for a fortress or fort was the fossa or ditch. The excavated dirt formed the earthen vallum or rampart. This ditch was usually up to 2m (6.5ft) deep and 6m (19.6ft) wide.¹² Many forts had two V-shaped fossae that included obstacles such as an abatis. In front to many of the ditches there were ‘Caesar’s Lilies’, a Roman equivalent of a minefield. These were pits about 1m (3.3ft) deep containing a sharpened stake usually camouflaged with a covering of vegetation. Caltrops may have served as obstacles as well, but evidence of their use is limited.

Examples of Roman forts. Top: Legionary fortress. Bottom: Auxiliary fort.

The earthen rampart or vallum, was 2m (6.5ft) or more in width and about 3m (9.8ft) high.¹³ It was covered with slabs of sod (turves) to hold the soil in place and prevent it from washing away into the ditch. The vallum was topped by either wooden palisades or stone walls depending on the era and location. For much of the first century

AD

the rampart was made only of earth. After

AD

50 it appears that the ramparts received a stone face if it was not already made of stone or brick as the fortifications took on a more permanent nature. Some researchers have determined that a well-built earthen fortification could last many years before it needed restoration. However, if they were occupied for a few years or decades, it is only logical that the garrison performed maintenance as needed and probably had to clear the fossa often to maintain its V shape. The Romans certainly did not consider the turf-and-timber structures as temporary since they maintained some of them for decades. Sometimes, stone was used to replace wooden features during the repair phase not only of the walls and towers but also of the interior buildings. Stone walls, like the wooden ones, had crenellations. Wooden walls were as thick as the timbers used and placed upon the earthen rampart, which usually had a firm foundation. When stone walls replaced the wooden ones, the soldiers had to cut back part of the front of the earthen rampart to allow for space for the new wall unless it was a new fortification built from scratch. On the sites rebuilt in stone, the earthen rampart remained behind the stone wall as reinforcement unless buildings were later added. Historians seldom agree on the thickness of the stone walls since few examples remain and those that still survive vary in width. When a stone wall was built it often consisted of a core of rubble instead of actual blocks of stone and its thickness varied, averaging 3m (9.8ft). In contrast, stone walls built into the rampart to replace wooden ones were 1m to 1.5m (3.3ft to 4.9ft) thick. The height of the walls is difficult to determine, but most sources give an average of 4m (13.1ft).¹⁴ According to M.C. Bishop, the walls of the fortress of Albing, located in Austria at the confluence of the Danube and the Enns, ranged from 1.8m to 3.5m (5.9ft to 11.4ft) in thickness and up to 5m (16.4ft) in height at the level of the wall-walk.¹⁵

The gates and towers were distinctive features of Roman legionary fortresses and auxiliary forts. Gates were flanked by a tower on each side. Towers also stood at each of the rounded corners and between the corner tower and entrance gate there were one or more intermediate towers depending on the size of the site. Some forts had neither intermediate towers nor a tower at every corner. Wooden towers supposedly could mount the Roman artillery (ballista), but stone towers offered more defensive benefits. Wooden towers were relatively simple while the stone ones often included arched windows with shutters and, in the case of those adjacent to the gate, a tiled roof. Wooden towers were usually square; the stone ones also tended to be square in the beginning, but later acquired a ‘U’ or ‘D’ shape whose rounded section projected beyond the fort’s walls thus covering the walls and the entrance.

The area enclosed by the walls varied in size. Early in the first century

AD

, the army created double legionary fortresses that held two legions. A regular fortress for a single legion could reach up to 500m (547 yds) in length and occupy up to 25 ha (62.5 acres), making it virtually a small town. By the second century, its size shrank to 10 to 15 ha (25 to 37.5 acres). The auxiliary forts occupied a smaller area since they were often intended only for a cohort of about 500 men. Fort Valkenburg, a typical square fort measured about 120m x 120m (131.2 yds x 131.2 yds) and occupied 1.4 ha (3.5 acres). Some of the larger auxiliary forts covered 4 to 6 ha (16 to 30 acres). Auxiliary forts had a number of common features, but they did not include all the facilities found in a legionary fortress. Some of these forts were so small that archaeologists have called them fortlets because they lacked a principia (headquarters facility) and held less than a cohort. There was also a smaller type of fortress of intermediate size between auxiliary forts and legionary fortresses. They were called vexillation fortresses because they housed a detachment from a legion. The Concise Oxford Dictionary of Archaeology defines them as temporary bases for detachments (vexillatio) of 2,500 to 4,000 troops from a Roman legion and occupying an area of 6.4 ha to ha.¹⁶

Comparison of First-Century Legionary Fortresses to Eighteenth- and Nineteenth-Century Forts

Fortification Terminology of the Roman Empire

The distinction between fort and fortress has never been easy to make. Duncan Campbell, author of Roman Auxiliary Forts, points out that early archaeologists used the Latin terms ‘castra’ for Roman fortresses and the term ‘castellum’ for forts. The latter generally applied to sites built for auxiliary units, but not always. According to modern terminology, the Roman fortress was greater in size and strength than the auxiliary fort and was even, in some cases, a fortified city. It included most of the amenities of a Roman town. During the reign of Augustus and later, the founding of Roman towns and colonies, mainly by veterans, was part of the Roman strategy of establishing a hold on conquered lands.

Terms associated with parts of Roman fortifications include vallum, porta, praetorium, principia, barracks and balneum. They are found in De munitionibus castrorum, the work of a little-known Roman writer of the late second century

AD

and contemporary of Trajan called Hyginus Gromaticus or Pseudo-Hyginus. According to Hyginus, the entrenched camp of Gelligaer covered up to 40.5 ha (100 acres) and was capable of holding 30,000 men. However, John Ward, author of The Roman Fort of Gellygaer, points out that there is no evidence that this particular site was as large as Hyginus claimed. Another contemporary source of information about the Roman military and its fortified camps was the fourth century

AD

writer Publius Flavius Vegetius Renatus. The only other description of a Roman entrenched camp is to be found in The Histories of the Greek Polybius who composed his work about three centuries earlier during the second century

BC

. Some illustrations of the Roman fortifications are found on Trajan’s Column in Rome. The Notitia Dignitatum (The List of Offices) from the late fourth century listed commanders, their units and the places where they were stationed. Otherwise, information from ancient sources is rather scant.

Agger – raised work including an earthen embankment or rampart with no revetment.

Armamentarium – armoury.

Auxilia – usually foreign troops from around the empire hired to serve as light troops. They often included such specialists as archers, slingers, light cavalry, etc.

Balneum – bath.

Basilica – the cross-hall in the principia with an oblong shape, colonnaded and semicircular apse used for trials or assemblies.

Burgus (p. burgi) – small town, military tower or castellum.

Canaba (pl. canabae) – hut, the plural term refers to a group of huts i.e. the civilian settlement adjacent to a fort.

Campus – training area or field.

Castellum – small military camps or civilian community.

Castrum (pl. castra) – military camp of any size. There were no Latin terms, except for castellum, to distinguish these fortifications by size or to indicate whether they were temporary or permanent (field camps, forts or fortresses).

Castra hiberna or Castra stativa – winter camps or forts that were permanent.

Castra aestival – temporary summer camps built during the campaigning season in enemy territory.

Castra stativa – permanent or static camp.

Centuria – barrack block.

Civitas (pl. civitates) – planned town founded by Roman officials.

Cohort – a force of about 500 men. Usually ten cohorts to a legion, the first being larger than the others

Colonia (pl. coloniae) – Roman settlements (colonies) in occupied territory. During the first century

AD

they were formed from retired veterans. They included Arles, Narbonne, Colchester, Lincoln, York and Merida and many others. Arles and Merida were founded in the first century

AD

.

Fabrica – workshop.

Fossa – the defensive ditch, usually V-shaped.

Groma – survey instrument used for laying out the camp or fort.

Horrea – storage building, including granaries.

Intervallum – space between the walls and buildings inside the fortification. Porta – door or gate.

Porta decumana – rear gate.

Porta praetoriana – main gate.

Praetorium – commanding officer’s quarters, usually adjacent to the headquarters.

Principia – headquarters.

Thermae – (thermal) baths.

Turris (pl. turres) – watchtower or turret.

Valetudinarium – hospital.

Vallum – walls or ramparts of a fortification. Some authors use this term instead of fossa.

Via decumana – road leading to the rear entrance (porta decumana) of the fort.

Via praetoriana – main road leading to main entrance (porta praetoriana). Via principalis – main road that runs between the two side entrances – porta principalis sinistra (left) and porta principalis destra (right).

Vicus – settlement, they usually appeared near forts and fortresses. See civitates.

The principia or headquarters was the heart of all fortifications. It was generally located in a central position at the intersection of main road or via praetoriana and a lateral road running between the two side gates. When the fortification was built of stone or was converted to stone, the principia was built like a forum with a peristyle courtyard that included in many cases a number of rooms, a hall with columns and a basilica. The hall and the basilica were reserved for official functions. Several of the rooms served as offices. A shrine included a place for the unit’s standards and a subterranean vault where money and other valuables were kept. Some of the rooms were used as an armoury.

The commander and his officers had their own quarters. The commander’s, located next to the principia, was called the praetorium. In a legionary fortress, it was large and included lodgings for the commander’s family and servants. It included an interior courtyard, a dining room, a kitchen, a bath and a toilet. In some cases, it comprised stables for his horses. The tribunes’ houses were similar but smaller. In newly-built or timber fortifications these structures may have been much simpler than in the stone ones.

Hospitals were found in fortresses, but they were not a common feature in forts because auxiliary units lacked the specialized personnel. Baths, on the other hand, were considered necessary for hygiene. However, they were often outside the ramparts because their heating system could be a fire hazard, especially when most of the structures were wooden. The baths included a changing room like a modern-day locker room in a gym. From there the men entered a series of warmer rooms with baths that became progressively hotter. One of the rooms was a steam room heated by hot air circulating beneath the floor and produced by heat from a furnace room. The hottest room was like a sauna. After cleaning their bodies with scrapers and even oils, they entered a cold bath. The private bath in the commander’s quarters had fewer features. To supply the baths, water was diverted from a nearby source (stream, river, etc.) and, if necessary, carried by an aqueduct to the fort entering near one of the gates to keep it under observation. It filled a large reservoir from which pipes, often made of lead, carried it underground to various points in the fort including the baths, the latrines and even smaller tanks the troops used for washing and cooking. The communal latrines