Roman Conquest of Britain: Caesar’s Expedition to Hadrian’s Wall

From the Lecture Series: The Celtic World

By Jennifer Paxton, Ph.D., The Catholic University of America

The Roman conquest of Britain played out over a long period of time. Even though Britain was viewed as a single country, it was populated by a diverse group of tribes. Some of these tribes already had substantial contact with the continent, while others were far removed. In the meantime, Rome was undergoing change as well. Let’s take a look at how Rome eventually conquered Britain.

Section of Hadrian's wall in Northumberland that still remains.
A portion of Hadrian’s wall from Cawfields quarry in Northumberland. Very little of the Hadrian’s wall still remains. The surviving sections are primarily scattered across the hilly central sector. (Image: Velella/Public Domain)

Pre-Roman Britain

Britain in the Iron Age was not politically united. It was divided among many tribes. Some of these tribal confederations were quite dominant in their respective regions. Sometimes these tribes allied with each other, and other times, they fought against each other. This, however, was a fairly prosperous society with elites that became wealthy, especially in the south and east, which had much richer agricultural lands.

It’s also worth noting that these British tribes were by no means isolated from the continent. The tribes in southeastern Britain adopted some of the traits of the more materially advanced cultures on the continent, including coinage.

Maiden Castle photographed from the air by Major George Allen in 1935.
Aerial view of the Maiden Castle in Dorset, which is the most famous surviving example of hillforts built by British tribes in the Iron Age. (Image: Major George Allen, Ashmolean Museum/Public domain)

The startling thing is that if you look at a map of the tribes that adopted coinage, you are almost looking at a forecast of the political map of Britain in the 20th century, with the south and east much more oriented toward Europe, and the north and west much more insular in orientation. The modern world is not so far from the Iron Age after all.

This was a diverse society, with various forms of political organization. Some of these tribes, but by no means all, built impressive hillforts, somewhat similar to the ones we see on the continent. A map of Iron Age hillforts in Britain reveals a very uneven distribution pattern across the island, with concentrations in the north, in Wales, and in the southwest. The most famous surviving example is at Maiden Castle in Dorset.

Learn more about Caesar and the Gauls.

Caesar’s British Expedition

In 55 B.C., while Julius Caesar, the Roman statesman, and military general, was in the midst of his campaigns in Gaul, he led an expedition to Britain. This expedition wasn’t very successful, so he came back the next year with a greater number of soldiers and managed to get some local British tribes to promise submission to Rome. Then Caesar left.

This British adventure of Caesar’s was mostly just an offshoot of the campaign in Gaul. Caesar seems to have been drawn to Britain partly because he thought some of the tribes there might have been giving aid and comfort to his enemies in Gaul; some of the British tribes may in fact have had family connections to Gaul, and they certainly had very close economic ties to Gaul.

Another reason may also have been that Caesar had heard rather exaggerated stories about the potential riches to be found in Britain; maybe there was lots of gold and silver there. Of course, this didn’t turn out to be true, and that may be one reason why Caesar didn’t bother to put more of an effort into conquering Britain.

This is a transcript from the video series The Celtic World. Watch it now, on The Great Courses Plus.

The most important reason he didn’t stick around was that he had all he could handle just subduing Gaul, and then he was off back to Rome to start a civil war. Caesar’s little British escapade had really been his own project, part of his private effort to secure riches and fame. It wasn’t really ‘official’ Roman policy at all. So, nothing much more happened between Rome and Britain for about a century.

Learn more about Celtic Britain and Roman Britain.

Roman Empire Invades Britain

In the century between Caesar’s expedition to Britain and the official Roman attempt to conquer Britain, a lot had changed for Rome. The Roman Republic had fallen, largely due to Caesar’s own actions, and the Roman Empire had risen. The imperial administration had grown much more elaborate. The second time Rome encountered Britain, it was much more of an official enterprise.

It all started in A.D. 43 under Emperor Claudius. Claudius decided he wanted some sort of a military triumph to boast about, and Britain was one of the last feasible places the Romans could conquer. However, unlike Caesar, Claudius was no general. He sent a much larger number of soldiers than Julius Caesar, who planned and carried out the campaign on his behalf.

Roman conquest of Britain from A.D. 43 to A.D. 84.
The various campaigns mounted by successive Roman Emperors, between A.D. 43 and A.D. 84, during the Roman conquest of Britain. (Image: Notuncurious/CC BY-SA 3.0/Public domain)

This time, though, the Romans were planning to stay. They made arrangements to collect tribute from a lot of the British tribes, particularly in the south and east. Over the course of the next 20 years or so, they established legions at several important strongholds in Britain, including Londinium, which of course became London, and Eboracum, which became York.

They established fortified sites throughout the country, and naturally, the Romans connected them to each other with their famous Roman roads. Now, the Romans were quite happy to work with what they found in Britain. The native inhabitants had already figured out the best routes across the country based on the terrain, so a lot of times, the new Roman roads were based on existing native British trackways, but the big contribution of the Romans was that they paved the roads and made them straighter.

Some of these roads are still quite important in English life today. The Roman engineers were so good that when later engineers needed to plan the modern motorways, they often just used the routes of the Roman roads. Watling Street, for example, a great road that led northwest from Dover to London and then from London to Wroxeter, gave us the route for the A2 and A5 Motorways. So many English workers today can thank the Romans for their daily commute.

Learn more about who the Celts are.

Hadrian’s Wall

While a large number of British tribes in the south and east formed agreements with the Romans, the same wasn’t true for most of the tribes in the north of Britain. Even in the south, the Romans encountered rebellious tribes and had to engage in battle with them. However, by the 2nd century, it became clear to the Romans that they had to make a decision about the northern tribes.

In the early 2nd century, the Romans built a wall clear across what is now northern England, under Emperor Hadrian. The wall started from the mouth of the Tyne River in the east and continued till the mouth of the Solway Firth in the west, to mark off the territory they were prepared to defend.

To the south of the wall was a civilized territory. To the north, there were barbarian tribes, people who painted themselves blue and fought naked, people the Romans were just as happy not to mess with.

The Romans found out why they shouldn’t mess with these people by trying to build a wall a little further north a few decades after Hadrian’s Wall. This was the Antonine Wall, which ran from the Firth of Forth in the east, near what is now Edinburgh, to the Firth of Clyde in the west, near what is now Glasgow.

The Antonine Wall proved to be too far north, and the Romans basically had to abandon it. Hadrian’s Wall became the limes or boundary of the Roman Empire. Incidentally, that’s where we get the English word ‘limit’ from, the Latin word limes.

So, Romans first encountered Britain, with the objective of conquering it, in 55 B.C. This, however, was primarily a personal adventure of Caesar. The official Roman conquest of Britain began in A.D. 43 and continued right through to A.D. 122 when the construction of Hadrian’s Wall took place. The construction of the Antonine Wall happened in A.D. 142. Even after this northern tribes continued to rebel against Roman rule, which forced the Roman Empire to maintain forts in the north to defend its position.

Common Questions about the Roman Conquest of Britain

Q: When did Rome conquer Britain?

Julius Caesar had first invaded Britain in 55 B.C., but this wasn’t an official Roman attempt to conquer Britain. Almost a century later, in A.D. 43, Emperor Claudius officially invaded Britain, and by A.D. 87 the Roman conquest of Britain was mostly completed.

Q: How did Romans conquer Britain?

The Roman Empire, under Emperor Claudius, invaded Britain in A.D. 43. They engaged in a number of battles with British tribes over a period of about 50 years. They thwarted the uprising in A.D. 60 and defeated all British tribal rebellions. By A.D. 87 they had conquered most of Britain.

Q: Did Rome conquer England?

Yes, the Roman Empire invaded and conquered the majority of the British Isles. The Roman conquest of Britain included modern-day England and Wales, and a small portion of modern-day Scotland. In A.D. 122, they built Hadrian’s Wall across what is now northern England, which started from the mouth of the Tyne River in the east and continued till the mouth of the Solway Firth in the west. The region south of this wall was Roman Britain.

Q: Why did Rome conquer Britain?

When Julius Caesar invaded Britain in 55 B.C., it might have been because he was displeased by the help the British tribes in the south the east provided Gaul. However, he didn’t really have the intention of conquering Britain or staying for long. When Emperor Claudius invaded Britain in A.D. 43, he wanted a military triumph to boast about, and Britain was one of the last feasible places the Romans could conquer.

Keep Reading
Ancient Celtic Culture: Fierce on and off the Battlefield
Viewing the Ancient Celts through the Lens of Greece and Rome
Historical Evidence and the Celtic Identity