6 Battles that Significantly Affected the Roman Empire

2 – Battle of Teutoburg Forest (AD 9)

A number of historians claim this battle was one of the most important in world history. It pitted a Roman force led by Publius Quinctilius Varus against an alliance of Germanic tribes led by Arminius. The battle occurred in September AD 9 in Lower Saxony and resulted in a decisive victory for the Germanic tribes.

Varus had been sent to consolidate the new province of Germania a few years earlier and he apparently angered Germanic tribes by disrespecting their culture and hitting them with heavy taxation. This caused grave unrest amongst Germanic tribes and by AD 9, this was in danger of becoming open rebellion. In September of that year, Varus led at least 15,000 men towards permanent military bases near the Rhine and he was investigating reports of an uprising.

According to ancient sources, Arminius had planned to release these fake reports in the hope of luring the Romans into a trap. Varus even ignored the warning of a local chieftain who said Arminius was a traitor. Arminius instructed the Romans to take a short detour into rebel territory and soon, the Roman army was stretched out across several miles. Heavy rain caused the army to become even more stretched and confusion reigned.

Once they had the Romans where they wanted them, the Germanic tribes surrounded them on all sides and engaged in guerilla-style assaults. The Romans marched on but were worn out by the constant attacks and terrible conditions. After a couple of days of hit and run tactics, the Germanic tribes closed in for the kill. Varus elected to commit suicide rather than risk capture and the majority of his commanders followed suit. The leaderless remainder was cut down almost to a man in what was described by ancient historians as a brutal slaughter.

Approximately 10% of Rome’s entire imperial army was wiped out at Teutoburg Forest and Emperor Augustus was enraged. Although Germanicus led successful Roman campaigns to the Rhine over the next few years, these attacks were mainly to restore honor. By AD 16, it was decided that the cost of keeping an army beyond the Rhine was too great and thus, Rome’s Germanic expansion was halted.

According to historian Peter S. Wells, almost all of modern day Germany and the Czech Republic would have come under Roman rule had Teutoburg Forest not happened while the lengthy and bitter conflict between Germany and France may never have occurred.

3 – Battle of Chrysopolis (AD 324)

This was the final battle between Emperor Constantine I and Emperor Licinius and took place on 18 September AD 324 in the city of Chrysopolis in what is now modern day Turkey. To the combatants, it probably appeared as if this was a battle of religions as Licinius had displays of Rome’s pagan gods in his battle lines whereas Constantine fought under the Christian standard.

Licinius was already on the back foot in the Second Civil War after suffering defeats at Adrianople and Hellespont. The Battle of Chrysopolis was a complete rout in favor of Constantine as he totally outwitted his opponent. Licinius is said to have lost up to 30,000 men in the battle and thousands more fled the battlefield.

The retreating Licinius knew he had no hope of victory and elected to throw himself at the mercy of his rival. Initially, Constantine showed mercy; perhaps because his enemy was married to his half-sister. However, he broke his solemn oath and executed Licinius a few months after Chrysopolis; presumably because he didn’t want any further rivals to his crown. To this end, he also had Licinius’ son executed the following year.

The battle had a major impact on the Roman Empire going forward. Constantine became the first sole emperor of Rome since AD 286 and soon after his victory, he decided to give the Eastern part of the Empire its own capital. The Emperor chose the city of Byzantium as the capital in the East which was renamed Constantinopolis. This city was to become the capital not only of the Roman Empire in the East but also of the brief Latin empire of the 13^th century and the Ottoman Empire which followed the fall of Rome in the East.

4 – Battle of Adrianople (AD 378)

This shouldn’t be confused with the battle of the same name which involved Constantine I in AD 324. Instead, I am referring to the Battle of Adrianople which took place on 9 August AD 378 between the Romans and the Goths. At this point, the Roman Empire was weakening and Emperor Gratian in the West and Emperor Valens in the East had their hands full with the strengthening Gothic tribes.

The Battle of Adrianople took place in the Eastern part of the empire in what is now known as the city of Edirne, Turkey. In AD 376, Valens made what was to be a momentous error by allowing the Visigoths to settle south of the Danube. He did so after they requested assistance since their land had been taken by the Huns. One side of the story says the Romans attacked the Goths after the latter refused to give up their weapons as one of the terms of settlement. Another version suggests the Romans treated the new settlers harshly which led to conflict.

Either way, Valens decided to march from Constantinople to attack the Goths but since the enemy numbers were so large, he asked Gratian for assistance. The Emperor in the West was delayed but eventually, Gratian made his way east. Incredibly, Valens then decided not to wait for his fellow emperor to arrive and marched on Adrianople, an inexplicable blunder which has baffled historians ever since.

Valens’ army was tired after a long march over heavy terrain and he made yet another mistake by attacking the Goths too soon. He either didn’t know that their cavalry wasn’t there or assumed they had left on a raid. Once he launched his attack, the nearby Gothic cavalry (after being informed of the attack) appeared on the scene and completely destroyed the Roman light cavalry which was unable to handle its superior enemy. The heavy Roman infantry was then surrounded and annihilated by Gothic cavalry charges. Valens was apparently killed in the fighting (his body was never found) and there were an estimated 40,000 Roman casualties.

Adrianople was a key moment in world history and is often cited by historians as the beginning of the end for the Western Roman Empire. Although the empire continued for almost another century, these years were marked by a gradual weakening before eventually crumbling.

5 – Battle of Yarmouk (AD 636)

The Battle of Yarmouk is probably not as well-known as it should be given its enormous historical significance. It pitted Byzantine forces led by Emperor Heraclius against the Rashidun Caliphate. It was a six day battle which began on 15 August AD 636 near the River Yarmouk along the modern day Syria-Jordan and Syria-Israel borders.

Heraclius had enjoyed a succession of victories against the rival Sassanid Empire but a quarter of a century of constant warfare wore down both sides. By AD 634, Arab forces had begun to invade the Byzantine east with a series of small raids. Impressive victories at Ajnadayn and Pella caused the influence of Christianity in the Levant to weaken and when Damascus fell to the Arab forces in AD 635, it was clear to Heraclius that he needed to check their advance before they became unstoppable.

He wanted to quickly regain Damascus and raised an army to march on the city. The Arab forces abandoned their Syrian raids and retreated to the River Yarmouk. The armies actually met in May AD 636 but the Byzantines didn’t engage until the middle of August. This was a huge mistake as it gave the Arabs time to reinforce, close off the Deraa Gap and scout enemy positions. The closure of the Deraa Gap was to prove critical as it prevented the Byzantine army from safely retreating.

Even though the Byzantines held an estimated 4:1 advantage in manpower, the tactical ability of Khalid ibn al-Walid was a major factor in the Arab victory. The Arab forces managed to gradually gain the upper hand and on the sixth day of the battle, their cavalry routed their Byzantine counterparts and this enabled them to attack the enemy rear which led to a retreat. However, the Byzantines had nowhere to run and were slaughtered by the well-trained Arab army. Casualty estimates vary but it is believed that the Byzantines lost up to 70,000 men in the Battle of Yarmouk.

The defeat resulted in the Byzantines permanently losing Syria, Palestine, Egypt and even parts of Mesopotamia. It also led to the quick collapse of the Sassanid Empire which was easy prey for the marauding Arab army. In addition, it led to the first great wave of Islamic conquests after Muhammad’s death and resulted in the rapid advance of Islam into previously Christian areas.

6 – Battle of Manzikert (1071)

According to some historians, the Battle of Manzikert was the beginning of the end for the Byzantine Empire. The battle occurred on 26 August 1071 between the Byzantines and the Seljuk Turks. The Seljuk Sultan, Alp Arslan, was happy to allow his Turkish allies to plunder land in Armenia and Asia Minor in the 1060s. They destroyed the Armenian capital Ani in 1064 and four years later, Byzantine Emperor Romanus IV led a campaign against the Seljuks but their infantry was too slow to complete.

While his commander Manuel Comnenus had initial success against the Turks, he was defeated. However, Arslan was happy to accept a peace treaty in 1069 as a means of ensuring his army could concentrate on the Fatimids who he saw as his main problem. There are now a couple of differing versions of history.

In one version, Romanus began another campaign, this time to Manzikert in 1070 where he made an offer to Arslan. The Byzantines would give up the recently captured city of Hierapolis if the Turks gave up their siege of Edessa. He threatened war if the sultan didn’t agree. Romanus knew that Arslan would refuse and prepared his troops; Arslan refused and war ensued. Another version suggests that Romanus sent envoys to renew the treaty in 1071. Arslan agreed and abandoned the siege of Edessa in order to fight the Fatimids. Then the Romans quickly moved to regain their territories.

Ultimately, we know that Romanus and his army did march into Armenia to recover lost fortresses. It was a long and difficult march and the Emperor angered his army by bringing a luxurious baggage train with him while the troops suffered. Romanus marched forward in the belief that he would retake Manzikert quickly but was unaware of the fact that Arslan and his forces were nearby while the enemy knew the Byzantine army’s whereabouts.

The Emperor rejected a peace offer and the battle commenced with the Byzantines marching towards the enemy. They withstood the initial Turk arrow attacks but their left and right wings sustained serious damage. The hit and run tactics of the Turks whittled down the Byzantine army and they were forced to retreat. Unfortunately for the Emperor, once of his generals was also a political rival and he disobeyed the order and marched back to the camp.

Confusion spread and this gave the Seljuks the opportunity to attack and they quickly routed the Byzantine right wing. The left wing put up more resistance but fell and this left the Emperor exposed in the middle. He was captured but ultimately set free by Arslan after agreeing to a number of concessions. If Romanus thought he had escaped, he was sorely mistaken as he was murdered soon after returning home.

It was the first time that a Byzantine Emperor had been captured by a Muslim commander and it severely undermined the empire’s authority in Armenia and Anatolia. While it was by no means the worst defeat in terms of casualties (which were estimated at fewer than 8,000), it was a strategic disaster for the Byzantines and ensured that Anatolia was lost to Christendom. The empire lasted almost 400 more years but it never fully recovered from the loss at Manzikert.