Roman Britain: From Caesar's Invasion to the Saxon Kingdoms

For nearly four centuries, the island of Britannia stood at the northwestern edge of the Roman world — a remote, often rebellious, but always wealthy province whose garrisoned frontiers and bustling cities left a mark that still shapes the English-speaking world. The story of Roman Britain is one of conquest, accommodation, and ultimately abandonment, as the legions that once marched into Caledonian mist withdrew to defend a crumbling heartland.

The Celtic Tribes of Pre-Roman Britain

Before the Romans arrived, Britain was a patchwork of Celtic tribes living in hill forts, roundhouses, and oppida. The Catuvellauni held the rich lowlands of the southeast under King Cassivellaunus, while the Iceni farmed East Anglia, the Dobunni held the Severn valley, and the Brigantes dominated the north. The Durotriges of Dorset and the Dumnonii of Cornwall clung to the western peninsulas. These tribes minted their own coinage, traded wine and olive oil with Gaul, and worshiped local deities whose names survive in places like Aquae Sulis (Bath). Their painted warriors, war chariots, and druidic priesthood gave them a fearsome reputation across the Channel — and caught the eye of a Roman general looking for glory.

Caesar’s Expeditions (55–54 BCE)

In 55 BCE, Julius Caesar](/biographies/julius-caesar) launched the first Roman invasion of Britain, landing near modern Deal in Kent with two legions. The campaign was more reconnaissance than conquest: his army was harassed by chariot-borne warriors, his ships damaged by Atlantic storms, and he was forced to beat a hasty retreat after extracting tribute and hostages. The following summer he returned with five legions and 2,000 cavalry, crossing the Thames and storming the hillfort of Cassivellaunus. This time he imposed a formal submission on several tribes, but storms again wrecked much of his fleet, and he never returned. Caesar’s invasions planted the idea that Britain was Roman property, even if he never fully subdued it.

The Claudian Invasion (43 CE)

Nearly a century passed before the next invasion. By 43 CE the new emperor Claudius needed a military triumph to secure his shaky throne, and Britain offered a tempting target. Four legions — about 20,000 men of the future Roman legion — sailed from Boulogne under Aulus Plautius, landing at Richborough in Kent. The Catuvellaunian king Caratacus led fierce resistance, but his brothers betrayed him, and within weeks the legions crossed the Thames and stormed the British oppidum at Camulodunum (Colchester). Claudius himself arrived briefly to accept the surrender, returning to Rome for a lavish triumph. The new province grew rapidly: Colchester became the first Roman capital, and within a generation most of lowland Britain had been absorbed.

Boudicca’s Revolt (60–61 CE)

Roman rule came at a brutal price. Heavy taxation, the seizure of land, and the behavior of brutal procurators like Catus Decianus drove the Iceni and their neighbors to revolt in 60 CE. When Roman officials flogged Queen Boudicca and raped her daughters, she led a ferocious uprising that destroyed Camulodunum, Londinium (London), and Verulamium (St Albans), killing perhaps 70,000 Romans and Britons. The governor Gaius Suetonius Paulinus finally crushed her at an unknown site in the Midlands, reportedly slaughtering tens of thousands. Boudicca poisoned herself rather than be taken alive, and her revolt exposed the fragility of Rome’s hold on the island. A decade later the humiliated province was reorganized around a new capital at Londinium.

Hadrian’s Wall and the Northern Frontier

The northern tribes of the Brigantes and the warlike Caledonians kept Rome’s attention for the next two centuries. In 122 CE, the emperor Hadrian — a restless traveler who personally inspected the new province — ordered the construction of a wall across the Tyne–Solway isthmus. Hadrian’s Wall stretched 73 Roman miles (about 73 miles / 117 km) from Wallsend to Bowness-on-Solway, with milecastles, turrets, and 16 larger forts housing auxiliary units. It remains the most spectacular surviving monument of Roman Britain, and is detailed in the broader story of the Roman forts and frontiers that girdled the empire. In 142 CE, the emperor Antoninus Pius pushed even further north, building the shorter, turf-walled Antonine Wall across the central isthmus, but it was abandoned within twenty years, and Hadrian’s line became the permanent border.

Londinium and the Romanization of Britain

Despite the wars of the north, the south and Midlands became one of the empire’s most thoroughly Romanized regions. Londinium grew into a bustling port of perhaps 30,000–40,000 people, with a bridge, a forum-basilica, the great amphitheater beneath the Guildhall, and a riverside wall rebuilt in the 3rd century. Villas with mosaic floors, hypocausts, and painted plaster spread across the countryside — the Lullingstone Roman Villa and Chedworth in the Cotswolds, or the famously grand villa at Woodchester. Britons served in the Roman army as auxiliary cavalry, fought at Dura-Europus in Syria, and rose to the consulship in Rome. The society of Roman Britain blended Celtic and Mediterranean forms, and by the 4th century Christianity had spread from cities like York and Lincoln into the countryside.

The End of Roman Britain (c. 410–450 CE)

The province’s long decline began in the 360s, when Picts, Scots, and Saxons raided across the North Sea. In 367 CE the “Barbarian Conspiracy” struck simultaneously, exposing the weakness of the field army. The emperor Magnus Maximus, a Briton, marched his troops to claim the western throne in 383, and Constantius III’s failed restoration of order further stripped the garrison. In 410 CE the emperor Honorius, fighting the Visigoths in Italy, sent the famous letter telling the Britons to look to their own defense. The province was never recovered: by 450 CE Vortigern was reportedly hiring Saxon mercenaries against the Picts, and within a generation the Saxon kingdoms of Kent, Sussex, Wessex, and East Anglia had taken root. The story of this collapse, mirrored across the western provinces, is told in detail in the fall of the Western Roman Empire. Yet Roman roads, walls, and place-names — Chester, Lancaster, Doncaster, the street grid of so many English towns — still mark the landscape of the empire’s most stubbornly remembered frontier.