How Did The Romans Conquer Britain?

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The campaign of 54 BC was more successful. Caesar learned from his mistakes, assembling a much larger taskforce, one numbering five legions and a 2,000-strong cavalry. Landing unopposed, the Romans were too strong for the Britons and soon advanced across the Thames, after which they were approached by the Trinovantes, a tribe whose leader had recently been overthrown by the warlord Cassivellaunus. The Trinovantes offered aid and provisions to the invaders, as did other tribes. In return, Caesar restored the Trinovantes’ exiled leader Mandubracius as king and forced Cassivellaunus to surrender. Assured by the latter that no second coup would occur, Caesar – along with every last one of his soldiers – left Britain and travelled back to Gaul.

Read more | Did the Britons ignore the Roman invasion?

Decades of relative harmony between Britain and the Roman empire followed, with a number of new client kingdoms set in place. These states were ruled by local tribes who had aligned with Rome; under this system, military occupation by Roman legions wasn’t required.

By AD 40, though, the political landscape of Britain had become significantly more volatile. Led by Caratacus, the Catuvellauni tribe had overthrown the Trinovantes as the rulers of southern England’s most powerful kingdom, simultaneously banishing any Roman-sympathetic tribes into exile. That year, Caligula instructed some of his legions to practise military manoeuvres on the beaches of Gaul ahead of an apparent invasion of Britain, but this most unpredictable of emperors never ordered the campaign’s commencement. Three years later though, Caligula’s successor – his uncle Claudius – did just that.

Coming in to land

Not only did Claudius wish to restore, and even expand, Roman influence in Britain but, suffering from poor public opinion in Rome, he also understood how a military victory could greatly improve his standing. One of Rome’s most venerable senators, Aulus Plautius, was placed in charge of the invasion, an ambitious campaign drawn up on the pretext of simply reinstating Verica, the exiled Atrebates king.

There is a difference of opinion among historians as to where the invasion forces landed in AD 43. Some reports mention Kent’s east coast, while others favour a spot close to Noviomagus Reginorum, aka latter-day Chichester. (Indeed, to this day, an area of Chichester Harbour is still known as Roman Landing.) As the invaders landed in three divisions, both accounts could be correct, of course.

Within four years, the Romans had control from the Bristol Channel to the Humber

After offering stiff resistance at the two-day battle of the Medway near Rochester, the Britons retreated to the Thames and further beyond into the Essex marshes, pushed back by the Romans’ momentum. Plautius, though, chose to reduce the intensity while he awaited the arrival of Claudius to enjoy the triumph soon to come. Once the emperor reached Britain, the beleaguered Britons, represented by 11 different tribes, surrendered without any further loss of life. Claudius was gifted the victory and returned home to bask in the glory.

His troops, meanwhile, continued into the interior, pushing on in both westerly and northerly directions. The future emperor Vespasian was in command of the legions heading west and made steady progress as far as Exeter. The story was similar for those marching north. Within four years of the initial invasion, the Romans had total control of the southern half of England, from the Bristol Channel to the Humber.

Julius Caesar and troops going to war — Julius Caesar had previously attempted to invade Britain during the first century BC (above), but it was an effort led by Claudius nearly 100 years later that was ultimately successful. (Image by Getty Images)

Resistance to Roman incursions both further north and into Wales saw minimal territorial gains – minimal ambition, in actuality – until Nero’s ascendancy to the emperorship in AD 54. Under the determined new governor Quintus Veranius, and his successor Gaius Suetonius Paulinus, large swathes of Wales fell under Roman control.

Read more | What happened to Britain's lost Roman legion?

The resilience of the Boudica-led resistance in AD 60–61 may have ultimately failed to expel the Romans, but the latter’s expansionist ambitions were certainly put on hold while they dealt with the uprising in the southeast – and while they rebuilt their strongholds of Camulodunum (Colchester), Verulamium (St Albans) and Londinium (London), which Boudica’s rebels had successfully razed to the ground.

The conquest of Wales and northern England was complete by AD 80, after which there were also successful Roman incursions into Scotland. These were short-term advances, though, with legions required to relocate overseas to quash rebellions elsewhere in the empire. The result of this was that Scottish tribes reclaimed their territory and that Hadrian’s Wall, on which work began in AD 122, would represent the northern frontier of Roman-held Britain.

Nige Tassell is a freelance journalist specialising in history

This content first appeared in the January 2022 issue of BBC History Revealed