Julius Caesar’s First Invasion of Britain (55 BC)

We are provided with a commentary of Caesar’s British campaigns in his own memoirs; De Bello Gallico in which describes his first expedition in 55 BC is described in his Gallic Wars – Book IV Chapters 20-38. Anyone wishing to understand the background for Caesar’s British campaigns should perhaps start by reading Caesar’s own commentaries.

Gaius Julius Caesar

What follows is our own interpretation of the events described by Caesar with a discussion on the archaeological evidence for his campaigns in the British Isles.

Why did Julius Caesar want to Invade Britain?

Despite its trade links, the Romans saw Britain as on the edge of the known world, and at first glance it would seem an unlikely target for their aggression. What then motivated Caesar to pick a fight with an island so far removed from civilisation? Firstly, and importantly in the eyes of the average Roman, Caesar claimed it was self defence and he invaded Britain to protect Rome.

He understood that in almost all the Gallic campaigns succours [aid] had been furnished for our enemy from that quarter

Julius Caesar, Gallic Wars – Book IV Chapters 20

With trading and cultural connections between Gaul and south-eastern Britain, it was natural for Britain to support Gaulish resistance, and if the Britons were offering aid to the enemy, Caesar wasn’t starting a new war, but pursuing victory over Gaul.

Suetonius, a later Roman historian, suggested that Caesar apparently believed Britain would be an excellent source of pearls to add to his collection of gems and art. Seneca said Caesar could not bear the thought that the ocean might be a barrier to success.

The Tribes refuse to submit

As a prelude to his first expedition to Britain Caesar sent his friend, ally and former adversary Commius the Gaul, the King of the Gallic Atrebates tribe, across the English Channel to try to persuade the British tribes to submit to Caesar’s terms without forcing him to do battle.

He orders him [Commius] to visit as many states as he could, and persuade them to embrace the protection of the Roman people, and apprize them that he would shortly come thither

Julius Caesar, Gallic Wars – Book IV Chapters 21

Ceasar Sends out Reconnaissance

At the same time, however, he sent his trusted lieutenant Gaius Volusenus Quadratus, the commander of his cavalry during many of his gallic campaigns, in a fast trireme to scout suitable landing-places along the British coast.

He sends before him Caius Volusenus with a ship of war, to acquire a knowledge of these particulars before he in person should make a descent into the island, as he was convinced that this was a judicious measure.

Julius Caesar, Gallic Wars – Book IV Chapters 21

Volusenus returned after five days reconnaissance and submitted his report. He would have certainly explored the coast from Hythe to Sandwich, although failed to discover the harbour at Richborough, which was successfully used a century later. This failiure would have a profound effect on the success of Ceasars expedition this year and the next.

The following day, having heard no word from his Atrebatean ambassador, Caesar’s invasion fleet left Gesoriacum (Boulogne-sur-Mer) on the evening tide and set sail for Britain.

Caesar Crosses the Channel

For his first adventure beyond Oceanus Caesar’s fleet comprised some eighty ships, mostly requisitioned from the Veneti and other maritime Gallic tribes conquered in the preceding campaigns throughout Gaul. Besides a few specially-built triremes and a number of slower but more manoeuvrable libernae or war-biremes, the majority were sea-going, estuarine or even large riverine vessels, monoremed actuaria or merchant galleys, flat-bottomed barcae and high-keeled scaphae of a number of different shapes and sizes. Upon this motley collection of vessels Caesar had embarked two of his most highly-trained legions, Legio VII and Legio X, numbering in excess of ten-thousand seasoned veteran troops.

Caesar Crosses the Channel

Caesar had also made provision for transporting a substantial cavalry contingent for use during his initial assault on Britain, who were directed to another small port at Ambleteuse a little further along the Gallic coast where another eighteen riverine barges awaited their arrival. The number of auxiliary cavalry units which comprised this expeditionary force is not recorded by Caesar and modern estimates range from a single ala to three or even four alae, that is, between five-hundred to two-thousand men and horses.

Whatever its size, the cavalry contingent, presumably under the command of Volusenus, suffered a substantial delay during embarkation of their horses and as a consequence missed the evening tide. The transports carrying the cavalry finally sailed on the morning tide but even then they were forced to turn back due to adverse weather conditions. Caesar’s first expedition to Britain would be without cavalry back-up.

they were approaching Britain and were seen from the camp, so great a storm suddenly arose that none of them could maintain their course at sea; and some were taken back to the same port from which they had started;-others, to their great danger, were driven to the lower part of the island, nearer to the west; which, however, after having cast anchor, as they were getting filled with water, put out to sea through necessity in a stormy night, and made for the continent.

Julius Caesar, Gallic Wars – Book IV Chapters 21

Caesar approaches Dover

On 25th August 55 BC at about 9 am Caesar approaches Dover (Dubris), with the intention of landing. Dover’s natural harbour had presumably been identified as a suitable landing place. However he observed the British army and their war-chariots massing on the white chalk cliffs above, which dissuaded him from landing there, since the cliffs were so close to the shore that javelins could be thrown down from them onto anyone landing there. Seeing this hostile reception committee and being aware that he needed horses to keep the British chariots at bay, he kept his entire invasion force waiting at anchor off the coast of Cantium (the lands of the Cantiaci) until the remaining eighteen transport vessels carrying his auxiliary Cavalry arrived. He waited for over six hours.

Finally, at half-three in the afternoon with still no sign of his cavalry but with both wind and tide favourable, Caesar ordered his fleet to weigh anchor. The triremes, biremes and monoremes of the Roman invasion force then proceeded along the coast to the north-east, some of the larger ships towing smaller unpowered vessels behind them, shadowed all the while on land by the charioteers and foot-soldiers of the gathered British tribes. For ‘about seven miles’ Caesar guided his ships until he came to the gently shelving shingle beaches between Walmer and Deal.

At first the sight of the British chariots charging up and down the beach – which the Romans had never before experienced in warfare – dissuaded Caesar’s troops from disembarking and joining battle. With their general being offshore aboard his trireme and unable to effect the morale of his troops in the initial landing force, it took the actions of a single unnamed soldier to turn the tide of battle. Seeing the invasion losing momentum, the standard bearer of Caesar’s Tenth Legion leaped overboard into the Cantium shallows shouting.

Leap, fellow soldiers, unless you wish to betray your eagle to the enemy. I, for my part, will perform my duty to the commonwealth and my general.

Julius Caesar, Gallic Wars – Book IV Chapters 25

With these words he waded forward carrying the legionary standard toward the waiting British. These actions prompted his fellow legionaries almost as a single entity to surge forward off the transport vessels and into the waves, choosing to follow the legionary standard into battle rather than suffer the shame and ignominy of allowing their revered holy symbol fall into enemy hands.

Standard Bearer of Caesar’s Tenth Legion leaped overboard

The battle on the beaches between Deal and Walmer was won by the experience and discipline of Caesar’s Roman legionaries, who put the British army to flight soon after they had gained a foothold on dry land.

Caesar Consolidates his Bridgehead Encampment

For the next few day Caesar was content to consolidate his bridgehead encampment and to receive the embassies of the British tribes, who now sued for peace with promises of hostages and tribute, also returning his own ambassador Commius the Gaul, whom they had kept imprisoned. On the morning of his fourth day in Britain, the eighteen ships carrying Caesar’s cavalry finally came into view of his encampment. Then things started going badly wrong for the Roman general. Just as the cavalry transports neared the British coast a squall blew up out of nowhere and threatened to dash the ships to pieces. The cavalry transports, which were so close to disembarking their cargoes of men and beasts, were forced back across the English Channel; miraculously all of them survived to make landfall back in Gaul. Luckily, the triremes and liburnae of Caesars fleet had been hauled ashore sometime before the weather turned, leaving the merchant galleys and transport vessels at anchor just offshore to bear the brunt of the storm’s ferocity.

The storm raged for the next few days, during which the Britons, seeing Caesar’s fleet being battered to pieces off the Kentish coast, took renewed courage from the Roman general’s misfortune and launched an ambush upon the Seventh Legion while it was foraging for food. Upon hearing of this British volte-face, Caesar mobilised the remainder of his troops and, leaving behind only a small reserve force to hold the bridgehead fortifications, he dealt the British forces a resounding defeat and managed to retreat with the majority of his army still intact, back to the relative safety of his encampment. Following this last encounter with the British army the storm abated and Caesar managed to effect repairs to all but twelve of his ships. With this accomplished, at nightfall he and his invasion army boarded their transports and departed Cantium, returning to the continent.

Evidence for Caesar’s Campaigns in Britain

Even though the autobiographical works of Caesar document both of his British campaigns they give very little geographical detail. He mentions no geographical location in Britain by name except Cantium and the River Thames (flumen Tamesin) and none of the other sites he describes may be positively identified. Even though he mentions the construction of several encampments on British soil no archaeological evidence of these fortifications has ever been found, indeed, we have nothing which can be conclusively attributed to either of Caesar’s expeditions.

It is perhaps noteworthy that Caesar’s autobiography states that during his second campaign, upon disembarking his troops he then looked for a place to encamp, implying that the fortifications he had established during his last excursion were no longer standing. These bridgehead fortifications built the previous campaign season may have been demolished by the people of Cantium, but it is much more likely that Caesar had himself ordered their demolition prior to departing Britain in 55 BC, to prevent them being used by the British to oppose his planned return to the island. This would have made sound military sense and it is very likely that Caesar demolished his substantial bridgehead fortifications of the following year before leaving Britain for the same reason, because it is evident from his autobiographies that he intended to revisit the island but was prevented from doing so by continued unrest amongst the tribes in Gaul and later by political machinations at Rome.

Evidence from the Continent

Even on the continent nothing of the preparations for Caesar’s British expeditions have been positively identified. The embarkation port for the first campaign is not mentioned by name but is assumed to have been Gesoriacum / Bononia (Boulogne-sur-Mer), but no Roman camps or buildings have been found here which may be dated to Caesar’s time. The point of departure for the second campaign is actually named as Portus Itius but this harbour has never been positively identified.

T. Rice Holmes in 1909 made a very good argument for Portus Itius being Wissant, about four miles east of Cap Gris-Nez, which was itself named Promonturium Itium by Ptolemy. Wissant has very little evidence for Roman occupation at any time, but there is an undoubtedly ancient camp lying in fields to the east of the modern village referred to locally as ‘Le Fort César’. This is, however, very wishful thinking, as the site in question is ovular in outline and measures roughly 88 x 53 m (c.289 x 174 feet), enclosing an area of only 0.4 hectares (just over one acre), which is hardly big enough to have housed a single cohort, let alone the three legions and two-thousand horse that are known to have been left behind at Portus Itius in 54 BC.

  1. Falstaff, from Will Shakespeare’s Henry IV : Part I – a bit anachronistic, I know, but still a valid axiom.

References for Julius Caesar’s Invasion of Britain

  • The Roman Invasion of Britain by Graham Webster (Batsford, London, 1980);
  • Rome Against Caratacus by Graham Webster (Batsford, London, 1981);
  • Britons and the Roman Army by Grace Simpson (Gregg, London, 1964);
  • Historical Map and Guide: Roman Britain by the OS (3rd Edition, 1956; 4th Ed., 1990; 5th Ed., 2001);
  • The History and Topographical Survey of the County of Kent: Volume 1 – From British History Online
  • A History of the County of Middlesex: Volume 1 – From British History Online The Council for Kentish Archaeology – Publishers of Kent Archaeological Review