Unique among the territories of the Western Roman Empire in the 5th century, Britain succeeded in holding back and even reversing the tide of Germanic conquest for nearly two centuries. This was an age of heroes… It was the Age of Arthur!

This is the eighth part of our discussion of Britain in the so-called Age of Arthur: the 5th though the mid-6th Century A.D. It is a fascinating period, with the Classical civilization of Greece and Rome giving way to the Germanic “Dark Ages”. It was the sunset of Celtic-Roman culture in Britain; it was the Age of Arthur!

But who was Arthur?

Before we answer that question, it is necessary we understand the world in which he lived.

(Read Part Seven here or start from the beginning here!


The last quarter of the 5th century was a grim time for those who looked to Rome, and the model of classical civilization it represented.

In 476 Romulus Augustulus, the teenage Western Roman Emperor, was forced to abdicate his throne by Odoacer,leader of barbarian foederati in Italy. The Western Emperor had long been a figurehead, with true power residing with the Magister Militum (“Master of Soldiers”); a position held in the 5th century largely by one Romanized-Barbarian officer after another (Flavius Aëtius being the chief exception).  Romulus had himself been placed on the throne by his father Orestes, one of these Romanized German commanders. Odoacer killed Orestes, and seized the Emperor in Ravenna.


The boy-Emperor’s life was mercifully spared: Odoacer granted him an estate in Campania and a life-time pension. But Romulus was the last to hold the title of “Western Roman Emperor” (Belisarius, the great Byzantine commander in the next century, would be offered this diadem and title by the Ostrogoths, which he refused). Odoacer went on to rule Italy thereafter as “King” and autonomous vassal of the Eastern Empire.

Few in the West likely noticed, much less cared. By this time, the provinces that once comprised the western half of the Roman Empire had been for some time under the control of various “barbarian” powers. Gaul was divided between an ever-shrinking Roman successor state (ruled by Syagrius, a noble Romano-Gaul who still bore the title of Magister Militum per Gallias) in the north-central portion of the province, the Franks in the northeast, the Burgundians in the southeast, and the Visigoths in the southwest.[1] Spain was divided between this same Visigoth kingdom (still centered in Aquitaine), and the German Suevi. North Africa, once the breadbasket of the Western Empire, was now a militant and piratical Vandal Kingdom centered on the former provincial capital of Carthage.

1418531.jpgOf the former provinces of the Western Empire only Britain fought on, resisting Germanic occupation. There are cogent reasons why Britain alone maintained its independence and identity.

The first is geography: as an island, Britain was not swamped by the wholesale invasion and migration of Germanic nations seen in the rest of the Western Empire. Only the Picts in the north were in a position to overrun the island and submerge its Roman civilization. That this did not occur is testament to the second factor: leadership.

From the first decade of the 5th century, when Rome abandoned the Britons to their own devices, strong leaders had emerged to maintain a loose unity among the Celtic Romano-Britons. These had been mostly successful and beaten back a host of raiders and invaders.

The first may have been Coel Hen (“Old King Cole”), perhaps the last official Dux Britanniarum (commander of the Roman forces stationed in the north of Britain) [2] ; and then Vortigern, prince of Powys and “High King” of Britain (See earlier installments in this series). These and lesser figures whose names and achievements are largely lost to history, managed to rally the island’s forces and coordinate a common defense for most of the first half of the 5th century. Vortigern’s long hold on power, however, saw the British position erode in the east of the island. The Germanic “Saxons” settled first as mercenary foederati and later as invaders (though the settlement of Anglo-Saxon foederati along the eastern coasts of Britain may date back to the late Roman occupation). Vortigern was followed by Ambrosius Aurelianus, who may have bore the title of Riothamus, or “Supreme King” among the Celtic petty-kings of Britain (see Part Six). Ambrosius struggled with mixed success to contain the Saxons in the eastern portion of the island.


A third and perhaps the most critical factor in the success of Britain’s defense against the tide of Germanic barbarism was cavalry.

Most Germanic tribes had their own cavalry traditions. While the majority of warriors tended to fight on foot, Germanic nobles and their retainers tended to serve as horsemen. Some nations, such as the Ostrogoths and Vandals, became primarily cavalry warriors as soon as circumstances and a ready supply of mounts allowed.

Not so the Anglo-Saxons.

These northern German/Scandinavian people were seafarers and pirates, who preferred to fight on foot. In battle they formed up in a tight, compact mass of infantry; as either a “shieldwall” or, when on the attack, the “swine array” or “boar’s head” (wedge) formation. Even though their nobles and their armed retainers might ride horses to the battlefield, these dismounted to fight.

Against true cavalry the Saxons were at a disadvantage. With no traditions of cavalry warfare of their own, they had developed no tactics to deal with horsemen, either light cavalry skirmishers or heavy cavalry shock troops, when confronting them.

It has been suggested by many historians that the Saxons were fearful of cavalry. While this may have been true to some extent (especially after stinging defeats at the hands of the British warlords), it is not likely from a cultural standpoint. Scandinavian chieftains and their household warriors rode horses to battle, as stated. The very symbol of the House of Kent, established by Hengist (or his successor), was a horse. But the horses of Scandinavia and the north German plains are small, sturdy animals, unsuitable for cavalry warfare. It was primarily for this reason rather than some kind of unreasoning terror of horsemen that the Saxons had no cavalry tradition of their own and were vulnerable to British cavalry.

Conversely, since the 3rd century, the importance of cavalry within the Roman Army had steadily increased. The emperor Gallienus, in the 260s, created a mobile cavalry corps stationed at Milan in northern Italy; which acted as a rapid-reaction force capable of responding to barbarian invasions anywhere along the broad frontiers of the Rhine or Danube. This was the prototype for the future “mobile field armies” (the comitatensis) of the later Empire. During the Roman occupation the Count of Britain (Comes Britanniae) commanded such a mobile field army, which included 1,800 cavalry[3].

While this force was likely withdrawn to support the imperial pretensions of Constantine III in 407[4], other cavalry resources were left at the disposal of Britain’s leaders for the island’s defense, and Britain may have owed its salvation to them.

In the 1st century AD, the nomadic Sarmatian people established dominance on the Ukrainian steppe. By the 2nd century these excellent horsemen had migrated into the mid-Danube region, coming into conflict with the Roman Empire. After defeating them in war, the Emperor Hadrian (or Marcus Aurelius) is thought to have settled 5,000 Sarmatian horsemen in Britain at Ribchester (Bremetennacum), as a reserve backing-up the garrisons along Hadrian’s Wall. It is not known if they brought their families with them,  or married local women. In either case, they continued to exist as part of the British population for the next two centuries. Sarmatian units are named as part of the Wall garrison till the very end of the Roman period in Britain. Though this is not in-and-of-itself proof of a continuing Sarmatian presence: units often retained ethnic names long after a particular ethnic groups ceased to comprise its members. But it is still likely that descendants of these Sarmatian settlers maintained their cultural traditions into the late empire.

1418542.jpgSarmatians depicted on Hadrian’s Column

Sarmatians aside, there were other heavy cavalry units stationed on the Wall and left there after Rome abandoned the province to its own devices. Many of these were “heavy” cavalry, and if names are to be trusted, at least one was a unit of catafractarii (very heavily armored lancers): the Equites Cataphractariorum at Morbio.

Further, the incipient northern British kingdoms of Strathclyde in the west and Gododdin in the east both maintained a tradition of cavalry warfare that may speak directly to their intermingling with and influence by the Sarmatian settlers under discussion (though the Celts in general have always had strong cavalry traditions of their own). The Roman authorities had established these friendly client peoples as a buffer(primarily the Votadini tribe, who later formed the Kingdom of Gododdin; and the Damnonii and Selgovae who together comprised the later Kingdom of Strathclyde). One factor preventing the Picts from overrunning the whole of Britain during the turbulent days following the Roman withdrawal, or later when the Saxons were ravaging the southern portion of the island during the 450s, was that between their highland kingdom, Alba, and Roman Britain stood the formidable mounted warriors of Strathclyde and Gododdin.

Sometime in the late 4th century or the first half of the 5th century, a large band of warriors from the Gododdin Votadini tribe, and their families, were settled in northern Wales. Led by the famous Cunedda, these founded the Kingdom of Gwynedd. It is likely that at least the nobles of Gwynedd maintained the cavalry traditions of their homeland in the north; providing the British leaders with still another potential source for cavalry.

The northern British horsemen were not the only source of good quality cavalry available to the defenders of Britain. Across the Channel, in Armorica, a group of Alans had been settled by Flavius Aetius when he was Magister Militum of the West during the reign of Valentinian III. Like the Sarmatians (to whom they were a close cousin) these were a nomadic people of the Eurasian steppe. Though originally a branch of the Central Asian Massagetae, they are often described as a Sarmatian people; and the distinctions between them might well have been slight. As discussed in previous installments of this series, it is likely the Alans merged with the British settlers who migrated to Armorica in mass in the mid-5th century.

Armorica was very likely allied with or even under the nominal authority of the British “Supreme King”; who in the later half of the 5th century was effectively Ambrosius Aurelianus. Geoffrey of Monmouth links Armorica with Ambrosius, as the place of his exile when hiding from Vortigern in the 440s. As discussed earlier, Alan horsemen may well have served in his Comitatus/Bucellarii (bodyguard regiment); and the Armorican Alani would have been available to the British military leadership (See Part Six).


Ambrosius Aurelianus took over the leadership of the Britons in the late 450s. For the next several decades he carried on a long struggle against Saxon, Pict and Scotti (Irish). While the bulk of British military garrisons and levied contingents would have been infantry, the military elite were cavalry. Only horsemen had the strategic mobility to respond rapidly to the midnight beacon on the hilltop, signaling “raiders from the sea”, or of a Saxon incursion across the “debatable lands”!

1418539.jpg Romano-British soldiers, mid-5th-6th century AD

Did Ambrosius personally respond to every alarm? As Riothamus of Britain only he had the authority to command the contingents of the various petty-kings of Celtic Britain. But the duties of “Supreme King” included more than leading armies; and not every incursion required the full response of Britain’s military resources.

Using the model left them by the Romans, the Britons would have layered their defenses. Fortress garrisons along the Saxon or Pictish frontier would deal with small-scale raids, and give advance warning of larger threats as they materialized. Local “petty kings” would then respond to such threats to their own territory; leading their household warriors, augmented when necessary by town militias and tribal levies.

When a threat too dangerous for the local ruler to safely deal with materialized, but not one so large as to require a general mobilization of the British kingdoms, then Ambrosius’ mobile cavalry force could be dispatched. Galloping up one of the numerous Roman roads or connecting byways to the endangered area, Ambrosius’ horsemen could be at any threatened part of the island in a week’s time. Like Gallienus’ 3rd century mobile cavalry corps, the arrival of a strong cavalry reinforcement under able leadership could shift the balance of any small engagement in favor of the British.

But galloping across the British landscape was young man’s work, the work of a capable subordinate.

Ambrosius Aurelianus’ birth date is unknown. If, as previously theorized, he was a youth fleeing Vortigern’s persecution in the 430s then he must have been in his middle years when he came to power in the late 450s. If we are correct in our assertion that Ambrosius is synonymous with “Riothamus”  then his wounding in Gaul by the Visigoths might have left him debilitated. While it is certainly possible for a vigorous older man to lead his warriors on hard campaigns, it is unlikely that Ambrosius was in any condition to gallop off at the head of his cavalry in response to every midnight alarm.

So who took over this role? Here, again, the late Roman practice suggests an answer.

In the late Roman Army, the supreme commander of Roman forces bore the title of Magister Militum (“Master of Soldiers”). He was assisted by a second-in-command, titled Magister Equitum: “Master of Horse”.

Ambrosius, “Last of the Romans”, must surely have been assisted by a trusted lieutenant, his “Master of Horse”. To this individual would be entrusted the command of the mobile cavalry force that kept the barbarians at bay.

Could this man, Ambrosius’ strong right-hand, have been Arthur?

1 arthur by scollins.jpg

If Arthur indeed existed at all, then it is probable that he led the Britons in the generation after Ambrosius. Ambrosius may have been alive until sometime around 500AD; though by this date he would certainly have been an aged, revered ruler. He must have groomed someone to take his place much earlier, perhaps as his Master of Horse.

Geoffrey of Monmouth’s “History of the Kings of Britain” has Arthur as Ambrosius’ nephew. Such a familial connection would certainly make a great deal of sense. Perhaps Ambrosius’ young nephew began his career within Ambrosius’ comitatus. Interestingly, the later British term for such bodyguard units of great leaders was Teulu: “Family”.


  1. The exact status of Armorica/Brittany is unknown, but might have been either an independent Romano-British successor state or a dependency of Britannia itself.
  2. Morris, John. The Age of Arthur, P54. Weidenfeld & Nicolson (1973)
  3. Jones, AHM. The Late Roman Empire. Johns Hopkins University Press (1986). The force under the command of the Comes Britanniae was composed of 6 units of cavalry, 2 legio comitatensis, and 1 regiment of auxilia. This mobile reserve numbered (on paper) 4,800 men: 300 troopers per cavalry vexillatio (1,800 total); 1,200 soldiers per legio (2,400 total); and 600 soldiers for the auxilia regiment. However, there is debate as to the size of the cavalry vexillations, and these may have numbered 600 instead; in which case the number of cavalry attached to the comitatensis of Britain would be, on paper, 3,600.
  4. Some of the comitatensis (mobile field army) of Britain may have been withdrawn a generation earlier still by another Imperial pretender, Magnus Maximus)


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  1. ritaroberts says:

    Another great read Barry So much information which I did not know about the cavalry. Thanks. Can’t wait for the next episode.

  2. Reblogged this on Tim Walker and commented:
    Great attempt at describing the murky waters of fifth century Britannia

  3. Looking forward to a piece on Arthur’s exploits, teasing out the reality from the legends, and the battle of Mount Badon.

  4. Pingback: THE AGE OF ARTHUR, PART NINE: THE ORIGINS OF ARTHUR | The Deadliest Blogger: Military History Page

  5. Pingback: THE AGE OF ARTHUR, PART SEVEN: SHADOW IN THE EAST | The Deadliest Blogger: Military History Page

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