The second Battle of Adrianople (August 9 378), sometimes known as the Battle of Hadrianopolis, was fought between a Roman army led by the Roman Emperor Valens and Gothic rebels (largely Thervings as well as Greutungs, non-Gothic Alans, and various local rebels) led by Fritigern. The battle took place about 8 miles or 13 kilometers north of Adrianople (modern Edirne in European Turkey, near the border with Greece and Bulgaria) in the Roman province of Thracia and ended with an overwhelming victory for the Goths.
Part of the Gothic War (376–382), the battle is often considered the start of the final collapse of the Western Roman Empire in the 5th century. Ironically, Adrianople actually was fought between the Goths and the Eastern Roman Empire, which ultimately withstood the Gothic invasions and developed into the Byzantine Empire.
Valens left Antioch for Constantinople, and arrived on the 30th of May. He appointed Sebastianus, newly arrived from Italy, to reorganize the Roman armies already in Thrace. Sebastianus picked 2,000 of his legionaries and marched towards Adrianople. They ambushed some small Gothic detachments. Fritigern assembled the Gothic forces at Nicopolis and Beroe to deal with this Roman threat.
Gratian had sent much of his army to Pannonia when the Lentienses (part of the Alamanni) attacked across the Rhine. Gratian recalled his army and defeated the Lentienses near Argentaria (near modern-day Colmar, France.) After this campaign, Gratian, with part of his field army, went east by boat; the rest of his field army went east overland. The former group arrived at Sirmium in Pannonia and at the Camp of Mars (a fort near the Iron Gates), 400 kilometers from Adrianople, where some Alans attacked them. Gratian's group withdrew to Pannonia shortly thereafter.
After learning of Sebastian's success against the Goths, and of Gratian's victory over the Alamanni, Valens was more than ready for a victory of his own. He brought his army from Melanthias to Adrianople, where he met with Sebastian's force. On August 6, reconnaissance informed Valens that about 10,000 Goths were marching towards Adrianople from the north, about 25 kilometers away. Despite the difficult ground, Valens reached Adrianople where the Roman army fortified its camp with ditch and rampart.
Richomeres, sent by Gratian, carried a letter asking Valens to wait for the arrival of reinforcements from Gratian before engaging in battle. Valens' officers also recommended that he wait for Gratian, but Valens decided to fight without waiting, ready to claim the ultimate prize.
The Goths were also watching the Romans, and on August 8, Fritigern sent an emissary to propose a peace and an alliance in exchange for some Roman territory. Sure that he would be victorious due to his supposed numerical superiority, Valens rejected these proposals. However, his estimates did not take into consideration a part of the Gothic cavalry that had gone to forage further away.
Valens' army may have included troops from any of three Roman field armies: the Army of Thrace, based in the eastern Balkans, but which may have sustained heavy losses in 376–377, the 1st Army in the Emperor's Presence, and the 2nd Army in the Emperor's Presence, both based at Constantinople in peacetime but committed to the Persian frontier in 376 and sent west in 377–378.
Valens' army was composed of veterans and men accustomed to war. It comprised seven legions — among which were the Legio I Maximiana and imperial auxiliaries — of 700 to 1000 men each. The cavalry was composed of mounted archers (sagittarii) and Scholae (the imperial guard). However, these did not represent the strong point of the army and would flee on the arrival of the Gothic cavalry. There were also squadrons of Arab cavalry, but they were more suited to skirmishes than to pitched battle.
Ammianus Marcellinus makes references to the following forces under Valens:
He also refers to the following officers:
Several modern historians have estimated the strength of Valens' army.
Treadgold estimates that, by 395, the Army of Thrace had 24,500 soldiers, while the 1st and 2nd Armies in Emperor's Presence had 21,000 each. However, all three armies include units either formed (several units of Theodosiani among them) or redeployed (various legions in Thrace) after Adrianople. Moreover, troops were needed to protect Marcianopolis and other threatened cities, so it is unlikely that all three armies fought together.
It is not possible to precisely list the units of the Roman army at Adrianople. The only sources are Ammianus, who describes the battle but mentions few units by name, and the eastern Notitia Dignitatum, which lists Roman army units in the late 4th to early 5th century, after Theodosius. Many units listed in the Balkans were formed after Adrianople; others were transferred from other parts of the Empire, before or after Adrianople; others are listed in two or more sectors. Some units at Adrianople may have been merged or disbanded due to their losses. The Roman forces consisted of heavy infantry, various archers and cavalry.
The Gothic armies were mostly infantry with some cavalry.
There were probably two main Gothic armies south of the Danube. Fritigern led one army, largely recruited from the Therving exiles, while Alatheus and Saphrax led another army, largely recruited from the Greuthung exiles.
Fritigern brought most if not all of his fighters to the battle, and appears to have been the force the Romans first encountered. Alatheus and Saphrax brought most of their cavalry, and possibly some of their infantry, to the battlefield late. These infantry were indicated as being an Alan battalion.
Ammianus records that the Roman scouts estimated 10,000 Gothic troops; but Ammianus dismissed this as an underestimate. This appears to be due to Alatheus and Saphrax's forces being away when the Roman scouts estimated the Goth's numbers before battle. Several modern historians have estimated the strength of the Gothic armies at 12,000–15,000.
On the morning of August 9, Valens decamped from Adrianople, where he left the imperial treasury and administration under the guard of the legions. The reconnaissance of the preceding days informed him of the location of the Gothic camp north of the city. Valens arrived there after marching for seven hours over difficult terrain.
At around 14:30, the Roman troops arrived in disorder, facing the Gothic camp that had been set up on the top of a hill. The Goths, except for their cavalry, took position in front of their wagon circle, inside of which were their families and possessions. Fritigern's objective was to delay the Romans, in order to give enough time for the Gothic cavalry to return. The fields were burnt by the Goths to delay and harass the Romans with smoke, and negotiations began for an exchange of hostages. The negotiations exasperated the Roman soldiers who seemed to hold the stronger position, but they gained precious time for Fritigern.
A detachment of Romans began the battle without orders to do so, believing they would have an easy victory, and perhaps over-eager to exact revenge on the Goths after two years of unchecked devastation throughout the Balkans. The imperial scholae of shield-archers under the command of the Iberian prince Bacurius attacked, but lacking support they were easily pushed back. Then the Roman left-wing reached the circle of wagons, but it was too late. At that moment, the Gothic cavalry, alerted by messengers from the embattled wagon circle, arrived to support the infantry. The cavalry surrounded the Roman troops, who were already in disarray after the failure of the first assault. The Romans retreated to the base of the hill where they were unable to manoeuvre, encumbered by their heavy armour and long shields. The casualties, exhaustion, and psychological pressure led to a rout of the Roman army. The cavalry continued their attack, and the massacre continued until nightfall.
In the rout, the Emperor himself was abandoned by his guards. Some tried to retrieve him, but the majority of the cavalry deserted. Valens' final fate is unknown; he probably died anonymously on the field, although one account says he was trapped in a nearby village house and burned.
According to the historian Ammianus Marcellinus, a third of the Roman army succeeded in retreating, but the losses were uncountable. Many officers, among them the general Sebastian, were killed in the worst Roman defeat since the Battle of the Teutoburg Forest, nearly four centuries earlier. The battle was a devastating blow for the late Empire. In effect, the core army of the eastern Empire was destroyed, valuable administrators were killed, and all of the arms factories on the Danube were destroyed following the battle. The lack of reserves for the army led to a recruitment crisis, which accentuated the strategic and morale impact of the defeat; but it is also clear that Adrianople did not mark the end of the Roman Empire, because the imperial military power was only temporarily crippled.
The defeat at Adrianople changed the character of the Empire in that it signified that the barbarians, fighting for or against the Romans, had become powerful adversaries. The Goths, though partly tamed by Valens' successor Theodosius I (who accepted them once more as allies), were to remain as a distinct entity within its frontiers; sometimes allies; other times enemies. Roman losses could only be made good by co-opting barbarians into the army as Foederati under their own commanders; and, as ever so often, military power has ways of translating into political influence.
Adrianople also changed forever the essential character of the Roman military. It was to end the reliance on the infantry legions, the formations that had proved so formidable in the past, and upon which the Empire had been built in the first place. Less than a hundred years after the battle heavy cavalry had become the main offensive arm in the Imperial army, changing by stages into the Byzantine cataphracts and the armoured horsemen of the Middle Ages. This however is still being heavily debated considering some sources do not mention any cavalry involvement against the roman legionaries and point out how they were probably occupied pursuing the fleeing roman cavalry. They argue that the victory was largely due to incompetence by the emperor Valens and incorrect information on the strength of the barbarians and the belief that roman legionaries had become incapable of gaining victory over barbarians is misguided. They stress that legionaries were always an effective killing machine and examples like the Battle of Châlons support this argument. It is widely considered that the fall of the Western Roman Empire was because of other economic, social, religious problems as well as incompetent emperors and constant civil wars which prevented the empire from focusing its forces upon the external threats, dismissing the argument that the roman legionaries were incapable of defending the late Roman Empire.