Prequel Roman Invasion Britain

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In the end, Caligula drew up his army in battle array on the shore of the ocean…and gave the order: “Gather seashells!”


Prequel Roman Invasion Britain


Claudius declared Britain was a country ‘where a real triumph could most readily be earned’. Several of the events leading up to the Roman invasion of Britain in 43 AD were bizarre based on accounts by Roman historians.

Britain's White Cliffs

White Cliffs Near Dover

Unlike the fierce battles of Caesar’s expeditions to Britain in 55-54 BC, the Claudian campaign did not meet any resistance when they first landed in 43 AD. Though Claudius claimed glorious victory, he only took charge at the end of the campaign. His role in the invasion appeared staged like a Hollywood production. He was in Britain for only sixteen days and took command of the following activities:

  • Ceremonial arrival
  • Treaty discussions with local chieftains
  • Battle for capture of Camulodunum (modern day Colchester)
  • Victory celebrations
Linnea at Roman Wall at Colchester

Linnea in front of Roman wall at Colchester

This article provides an overview of key events and players leading up to the invasion based on the historical accounts from Dio Cassius and Suetonius. Some archaeological experts propose the Claudian invasion was the last in a line of interventions, both and planned, that spanned the period between 55 BC and 43 AD. Some have suggested that there was already a Roman military force in Britain prior to the Claudian invasion. The invasion was nothing more than a peace-keeping expedition to annex Britain into the Roman Empire. This theory will be discussed further in a future post.

Colchester Sphinx Dated About 43 AD

Colchester Sphinx dated about 43 AD from Colchester

Aftermath of Augustus  

One of the greatest British kings, Cunobelin, was an astute politician who came into power about 9 AD. At this time, Emperor Augustus faced one of Rome’s most calamitous periods when Prince Arminius destroyed three Roman legions in Germany. Cunobelin maintained a balance of power with Rome by welcoming their traders into his capital, Camulodunum (modern day Colchester). Cunobelin reigned over the Trinovantes and the Catuvellauni.  A great statesman, he skillfully balanced between the bitterly opposing pro-and anti-Roman factions.

Caesar Augustus Marble Head

Emperor Caesar Augustus Marble Head

Augustus died in 14 AD and was succeeded by Tiberius. He accepted Augustus’ injunction to allow things to stay as they were and to concentrate on sound administration. Nonetheless, he renewed diplomatic activity with Verica (King of the Atrebates).

Tiberius Caesar Augustus

Emperor Tiberius Caesar Augustus

The final years of Cunobelin was marred by a family upset around 40 AD, when Caligula was Emperor. The elderly king appointed his pro-Roman son, Adminius, to rule the northeast tip of Kent. This area included the land-locked harbor along the southeast coast and the Wansum Channel into the Thames Estuary. It appears it was Roman policy to ensure that the main landing points remained in friendly hands.


Celtic Horned Helmet

The precise date of Cunobelin’s death is not certain, but it was within 1 year before or after 40 AD. His eldest son, Togodumnus, inherited the kingdom while the younger brother, Caratacus, struck out on his own to conquer other territories. Their brother, Adminius, was ousted from Britain about 40 AD and may have been connected with these events.

Caligula’s Staged Invasion

When Caligula visited his Germanian legions and auxiliaries in 40 AD, Adminius and his followers sought the emperor’s aid to restore the status quo ante. The Roman historian Suetonius said Adminius surrendered to Caligula after he had been banished by his father, Cunobelin. Caligula dispatched a message claiming all of Britain had surrendered to him. He ordered his couriers to drive their chariots all the way to the Forum and the Senate house to deliver his letter.

Status of Caligula on Horseback

Statue of Caligula on Horseback

Caligula then ordered all troops and siege engines to be positioned on the ocean shoreline for battle. It was as if he was ready to invade Britain. He embarked on a trireme (ship with multiple banks of rowers), sailed a short distance from shore, and then returned. He took his seat on a lofty platform and gave the soldiers the signal to charge with trumpeters urging them on.

Replica Ancient Roman Ship

Replica Ancient Roman Ship

No one understood what Caligula had in mind when he suddenly gave the order to gather seashells as plunder owed to Rome. He ordered the soldiers to fill their helmets and folds of their cloths with the ocean loot. Having secured these spoils, he became elated as if he had enslaved the ocean. He commemorated the victory by erecting a tall lighthouse where fires would guide ships at night.

Roman Soldiers in Formation

Roman Soldiers in Formation

Caligula gave his soldiers many presents and took their shells back to Rome to exhibit as bounty from Britain. He also selected a few German prisoners to parade in an extravagant triumph that he told his agents to prepare in Rome.

Although Caligula’s real plan is obscured by these wanton acts, he clearly intended to invade Britain. This may have been at Adminius’s urging. But the invasion was deferred, most likely as a result of mutinous soldiers refusing to cross the monster-infested British Channel.

In early 41 AD, Caligula was assassinated in Rome for his crazed behavior.

Rise of Anti-Roman Factions

The political strife in Britain did not come all at once, but by stages, starting with the removal of Adminius. Cunobelin felt he could entrust Admius with the strategically important area of Kent to rule. After the death of Cunobelin, Togodumnus and Caratacus pursued an expansionist policy even more vigorously than their father. And they did this with less respect for what seemed an indecisive and ineffectual Roman authority across the English Channel.

Dynasties of Southeast Britain

Date Rome Southern Dynasty Northern Dynasty
50 BC Civil War, Murder of Caesar;
40 BC Commius
30 BC Octavian and Mark Antony Civil War Addedomaros
20 BC Augustus Tasciovanus
10 BC Tincommius Dubnovellaunos
1 AD
AD 10 Epatticus Cunobelin
AD 20 Tiberius Eppillus
AD 30 Verica Adminius
AD40 Caligula Caratacus
AD50 Claudius

There was ongoing, bitter rivalry between the ruling houses of the Atrebates and the Catuvellauni. The control of lands in Kent teetered back and forth between these dynasties. The Atrebates laid claim to east Kent through King Eppillus, who reigned there from 5 to 20 AD until Cunobelin took back control.

Verica succeeded his elder brother, Eppillus, as king of the Atrebates about 15 AD. He established his capital at Calleva (modern-day Silchester). Verica’s territory was pressed from the east by Cunobelin’s brother, Epatticus, who conquered Calleva (modern day Silchester) about 25 AD.

When Epatticus died in 35 AD, Verica regained his original territory. Cunobelin chose not to challenge Verica. He instead honored Verica’s treaty agreement with Rome.

Map Ancient Britain 1st Center

Map Ancient Britain 1st Century

With the death of Cunobelin, the political balance tipped when Caratacus first took control of Kent from his brother, Adminius. Not content with this, he invaded south of the Thames. He succeeded where his uncle Epatticus had failed: gain control of territories in southern Britain and forge them into his kingdom. Sometime after 40 AD, he may have conquered a vast area of the Atrebates territory.

This time, the Verica took flight and sought protection from Claudius. Appearing as a suppliant before the emperor, Verica claimed he had been driven out of Britain by an uprising. He called upon Claudius to fulfill his obligation under their treaty to protect his sovereignty.

Clearly, critical land areas on the southeast coasts of Britain were now under hostile control and the political balance so skillfully developed and maintained by Augustus was in shambles. Evidence of further expansion of the Catuvellaunian power was provided by Dio Cassius in his Roman History. Soon after the Roman landing, Commander Aulus Plautius received the surrender of some Dobunni, who, he adds, were subjects of the Catuvellauni.

This gave the newly empowered Claudius a cast-iron justification for an invasion. Victory would elevate him to the same glory as Julius Caesar and divert Rome’s attention away from his relationship with the Senate which was charged with suspicion and hostility.

Imperial portrait of Roman emperor Claudius

Imperial portrait of Roman Emperor Claudius

To be continued:

The next post will highlight the Roman pre-launch activities that almost ended in disaster and the relative ease of the Legions to occupy Britain initially.


John Manley, AD 43 The Roman Invasion of Britain: A reassessment; Tempus Publishing, Inc., Charleston, SC, 2002.

David Miles, The Tribes of Britain; Phoenix, Imprint of Orion Books, Ltd., London, UK, 2006.

Gaius Suetonius Tranquillus, The Twelve Caesars, Translated by Robert Graves; Reprinted 2007 by Penguin Books, New York.

Graham Webster, Roman Invasion of Britain, Reprinted 1999 by Routledge, London.

Graham Webster, Rome Against Caratacus: The Roman Campaigns in Britain AD 48-58; Reprinted 2002 by Routledge, London.

Graham Webster, Boudica: The British Revolt Against Rome AD 60; Reprinted 2004 by Routledge, London.

Cassius Dio, Roman History, published in Vol. VII of the Loeb Classical Library, Edition 1924; Book LX*.html


7 Responses to "Prequel Roman Invasion Britain"
  1. Aquileana says:

    Claudius´ invasion certainly seems as if it was staged like a Hollywood production.
    one could say that he was very efficient so as to take command on those activities you mention in such a brief lapse of time.
    Also it is very interesting to read about Augustus and his successors Tiberius and Caligula… not to mention King Cunobelin, whose importance was remarkable as we could say from your previous posts. His death would lead not only to rivalries determined by the need to conquer power, but also to changes regarding the strategies involving expansion purposes…
    Excellent post, thorough and highly informative, dear Linnea.
    Thanks for sharing. All the best to you!, Aquileana 😀

    • Hi Aquileana,

      Thank you for your feedback on the post. The events leading to Rome’s invasion of Britain in 43 AD is fascinating. The Roman written accounts of Caligula are bizarre regarding his staged invasion of Britain. And the family upset with Cunobeln’s sons makes great drama. The archaeologists have not yet found sure-proof evidence of the massive invasion in 43 AD. The stiff British resistance did not occur until later with Caratacus and Boudicca.

      I appreciate your continued support and sharing your love of ancient history. Have a wonderful week.


  2. This post is very well-researched, Linnea! It is always so interesting to find out about the attacks, activities, and lifestyles in Britain through your posts as much of my family is from there. Thank you for such great detail too!

  3. Kiersten says:

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  4. Luciana says:

    Hi Linnea,

    A wonderful and informative article. I had to laugh reading about Caligula and his compensation. He never ceases to disappoint with his antics.

    Have a wonderful weekend.

    • Hi Luciana,

      Thank you for your wonderful feedback. I agree the historical accounts of Caligula is always fun to read. Most likely, he had a potential rebellion on his hands when his troops refused to go to Britain with him. The account that he had them gather seashells on the seashore was one of the strangest tales that I’ve read about him.

      As always, I always appreciate your thoughtful comments. Have a wonderful weekend.


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