Castrum to Castle

Classical to Medieval Fortifications in the Lands of the Western Roman Empire

J. E. Kaufmann, H. W. Kaufmann

• Publisher: Pen & Sword Military
• Year: 2018
• ISBN:
  9781473895829
• Topic: History
• Subtopic: Military & Maritime History
• Index: History

A richly illustrated history of military fortifications in ancient and medieval times. For over a thousand years, from the time of the Roman Empire to the classic period of castle-building in the twelfth and thirteenth centuries, fortified sites played a key role in European warfare. This highly illustrated history gives a fascinating insight into their design and development and into the centuries of violence and conflictthey were part of. The study traces the evolution of fortifications starting with those of the Romans and their successors. Included are the defenses erected to resist Islamic invasions and Viking raids and the castles built during outbreaks of warfare. As the authors demonstrate, castles and other fortifications were essential factors in military calculations and campaigns. They were of direct strategic and tactical importance wherever there was an attempt to take or hold territory. The factors that influenced their location, layout, and construction are analyzed in this fascinating book, as is the way in which they were adapted to meet the challenges of new tactics and weapons.

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 o...

Table of contents

• Cover
• Title
• Copyright
• Contents
• Preface
• Acknowledgements
• Chapter 1: The Roman Era
• Chapter 2: Fall of the Western Roman Empire
• Chapter 3: The Dark Ages in the West Part I
• Chapter 4: The Dark Ages in the West Part II
• Chapter 5: Transition from The Dark Ages to the High Middle Ages
• Chapter 6: Beginning of the Classic Age of Castles – the Twelfth Century
• Chapter 7: The Age of the Classic Castle – Twelfth to Thirteenth Centuries
• Chapter 8: From Wales to Italy – Twelfth to Fifteenth Centuries
• Conclusion
• Appendix I: Table of Monarchs
• Notes
• Glossary
• Bibliography