11 Famous and Most Powerful Roman Legions

The Roman Empire has been, without a doubt, one of the most powerful in the history of humankind. Extending over an area of 4.4 million km², it encompassed most of Western Europe, the Balkans, as well as parts of the Middle East, and the coast of North Africa. But how did the Romans manage to conquer such a vast land? Thanks to their legions, of course!

The legions were the largest military units of the Roman army. During the Roman Republic, from 509 BC to 27 BC, they were composed of 5200 infantry, a term referring to soldiers on foot, and 300 equites, military units mounting an animal.

With the start of the Roman Empire, from 27 BC onwards, their structure changed slightly. In this period, legions had 5600 infantry and 200 auxilia, which provided most of the Roman army’s cavalry and specialized troops. 

Legions were usually created for a specific reason and then disbanded, but some of them served the Roman Empire for more than six centuries. But which were the greatest and most powerful legions? Let’s find out! 

1. Legio III Gallica 

The Legio III Gallica was one of the many legions founded by Julius Caesar in 49 or 48 BC with the purpose of helping him in his civil war against Pompey the Great. The name ‘Gallica’ derives from the fact that most of the recruits came either from Provence, a region in southeastern France, or northern Italy.

Caesar’s civil war was one of the last conflicts of the Roman Republic before the beginning of the Roman Empire in 27 BC. The war lasted for four years and was fought in Italy, Egypt, Spain, Greece, and other territories. It ended with the victory of Caesar even though he was brutally assassinated soon after. 

Following the death of their leader, the Legio III Gallica became part of Marc Antony’s army fighting in the famous Battle of Philippi to avenge Julius Ceasar’s assassination. 

After the end of the Roman Republic, the legion kept serving under the Roman Empire and, after the Marc Anothony’s suicide, it was sent to the east, in Syria.

2. Legio V Macedonica

Unfortunately, we do not know much about the origin of Legio V Macedonica. According to evidence, it was probably created in 43 BC by Consul Gaius Vibius Pansa and Octavian, who later became the first Roman Emperor. 

We don’t have much data on the first decades of Legio V Macedonica, but historians agree that it probably fought in the battle of Actium. This war is today considered the climax of years of conflicts between Octavian and Marc Antony and is particularly important as it marks the end of the Roman Republic and the beginning of the Roman Empire. 

After this conflict, the veterans of Legio V Macedonica were sent to Veneto, a region in northwestern Italy, while second-generation veterans were sent to the refounded city of Berytus, today’s Beirut, the capital of Lebanon. 

Legion V got its name from its service in Macedonia from 30 BC to 6 BC and is currently the longest-lived Roman legion known to us, as it existed for more than 600 years. It would take too much time to mention all the wars and battles in which Legio V had been involved but here is a quick summary.

From 6 AD to 61 AD, Legio V Macedonica stayed in Moesia to guard the lower Danube frontier against the tribes of Dacia. It was then transferred to the southeast area of the Black Sea, where it participated in several wars and conflicts. The many people composing the Legio V Macedonica lived in these territories for about ten years and then returned to Moesia. 

For most of the third century, this legion was stationed in Potaissa, a military fort, located in today’s Romania. The last evidence we could find about Legio V dates back to 635 or 636 when at least part of it was situated in Egypt. 

3. Legio XII Fulminata

The Legio XII Fulminata was founded by Julis Caesar in 58 BC and served during the Gallic Wars. These conflicts lasted from 58 BC to 50 BC and were fought against the people of Gaul, a territory extending over today’s France, Belgium, as well as parts of the UK and Belgium. The conflict ended with the defeat of the Gaul populations and the annexation of this massive region to the Roman territories. 

The emblem of this legion was the thunderbolt, a symbolic representation of lightning accompanied by a thunderclap.  Under the Republic, the Legio XII Fulminata fought in the battle of the Sabis and the battle of Pharsalus, the decisive conflict that put an end to Caesar’s civil war. 

After the beginning of the Roman Empire, Legio XII Fulminata was defeated by the Phartians in the Battle of Rhandeia and later took part in the first Roman-Jewish war, losing in the battle of Beth Horon.

The legion was then sent to guard the Euphrates border and, in 75 AD was relocated to the Caucasus region. 

4. Legio IX Hispana 

The Legio IX Hispana was founded in the first century BC. 

We’re not sure about the exact origins of this legion, however, we know that it was stationed in Britain in 43 AD. Historians agree that Legio IX Hispana actually helped in the invasion of this area, led by Claudius and general Aulus Plautius.

Ths legion suffered a terrible defeat in 60 or 61 AD in the battle of Camulodunum also known as the Massacre of the Ninth Legion. During this war, a horde of British tribes attacked the Roman forces killing approximately 80 percent of the foot-soldiers in the legion. 

Legio IX Hispana was also involved in the conquest of Caledonia, today’s Scotland. No data on this legion was found after 120 AD. Modern scholars believe that it was destroyed in the 2nd century in Nijmegen, today’s Netherlands.

5. Legio X Equestris

If Julius Caesar had to choose a single legion among the many he founded throughout his career, it would have probably been the Legio X Equestris. This was the first legion founded by this Roman general and it fought with him in virtually all the battles of the Gallic Wars.

Legio X Equestris also helped Caesar defeat the Helvetii tribes, preventing them from moving from Switzerland to western France, and accompanied their founder in his conquest of Britain. 

The legion was disbanded in 45 BC, and its fighters were given lands in Narbonne, in southern France. 

6. Legio VI Victrix

Legio VI Victrix was founded in 41 BC by general Octavian. This legion started its career in 41 BC fighting in the Perusine War, a civil war in which Lucius Antonius and Fulvia supported Mark Antony against Octavian. Fulvia, who was married to Marc Anthony, did not want her husband to share power with Octavian, and that’s why, together with Anthony’s brother, Lucis, she raised eight legions in Italy. However, Octavian managed to win thanks to Legio VI Victrix.

Following the Perusine War, this legion fought in the Battle of Actium and then participated in the last phases of the Roman conquest of Hispania, a territory extending over today’s Spain and Portugal. 

Legio VI Victrix was then relocated to Britain where it helped in the construction of both the Hadrian Wall and the Antonine Wall. 

7. Legio XVIII

We, unfortunately, do not know the cognomen of Legio XVIII, and for this reason, historians refer to it by using its identification number. 

Legio XVIII was founded by Octavian in 41 BC and was probably created to deal with Sextus Pompeius, who, at the time, was threatening Rome’s grain supply from Sicily. 

Together with many other legions, Legio XVIII took part in the Battle of Actium and after this conflict was relocated to the Gaul region. In the first century BC, it was sent to the Germania provinces, becoming part of the huge army led first by Drusus and then by Tiberius. 

Legio XVIII was destroyed in the Battle of Teutoburg forest when an alliance of Germanic peoples ambushed the Roman forces. 

8. Legio III Cyrenaica 

The Legio III Cyrenaica was probably founded in 35 BC either by Mark Anthony or Lepidus. It fought in the battle of Actium and was then used to occupy Thebes, an ancient city in Egypt located along the Nile, about 800 km south of the Mediterranean Sea. 

Legio III was relocated to Alexandria around 7 AD or 9 AD and moved to the province of Arabia Petraea in 106 AD. The legion stayed here only for a few years and then returned to Egypt, probably to help in the Trajan Wars against the Parthians. 

In 125, Legio III Cyrenaica moved back to Arabia where part of it helped in the Bar Kokhba revolt, while another fought in Mauritania against the Mauri, a population located in today’s Morocco and northwestern Algeria.

The last data we have regarding this legion dates back to the fifth century and was found in Bosra.

9. Legio I Germanica

This was one of the legions founded by Julius Caesar to fight against his political rival Pompey. 

According to some historians, Legio I Germanica was established in 48 BC and got its name from the Battle at Ponte Longi against Arminius and his army. This war was fought in Germany under the command of Roman general Aulus Caecina Severus. Legio I particularly distinguished itself in this conflict and was therefore given the cognomen of Germanica. 

This legion also became famous for supporting Nero in 67 AD. In fact, during this period, many politicians were unhappy with Nero’s administration and started to see the governor of Hispania, Servius Sulpicius Galba, as a possible substitute.

Despite this, Legio I Germanica kept supporting Nero and helped him defeat Gaius Julius Vindex, one of the politicians supporting Galba. Unfortunately, the effort was useless as Galba was eventually elected as the new emperor. 

10. Legio II Augusta 

Legio II Augusta was founded in 43 BC and remained active till the 4th century AD. Its emblems were the Capricornus, Pegasus, and Mars. To this day, we are not sure whether it was funded by Julius Caesar or by consul Gaius Vibius Pansa.

Throughout its history, this legion has fought in several Roman territories ranging from Britain to Germania and Hispania. In particular, this legion took part in the Cantabrian Wars in Hispania and helped build the Colonia Acci and Cartagena. 

In Britain, Legio II fought several battles against the local tribes and was stationed first at Alchester and later at Waddon Hill, and Exeter. 

The last known mention of Legio II Augusta was found in the Notitia Dignitatum, a document of the late Roman Empire that located this legion in Richborough, on the coast of Kent. 

11. Legio XV Apollinaris 

Active from 41 BC to the fifth century AD, Legio XV Apollinaris used a picture of Apollo or one of this god’s sacred animals as an emblem. This legion was founded by Octavian to end the occupation of Sicily by Sextus Pompeius, who kept threatening Rome’s grain supply. 

Following this episode, Legion XV fought in the battle of Actium, and in 6 AD, took part in Tiberius’ campaign against the Marcomanni, a Germanic population who established a powerful kingdom north of the Danube.  

The legion was then sent to the east and stayed in Syria, and Armenia. In 66 AD, it fought in the first Jewish Revolt and captured the towns of Jotapata and Gamla. 

Legio XV was then sent multiple times to Parthia, a region located in northeastern Iran, to fight in several wars. 

Conclusion

Even though nowadays we only remember generals such as Julius Caesar and Marcus Antonius, it is important to keep in mind that they would have not gone far without their legions.

If the Roman Empire was able to become one of the largest and most powerful ones in the history of mankind is only thanks to them.