Roman conquest of Britain

Beginning with an invasion ordered by the emperor Claudius in 43 CE, the Roman Empire spent roughly four decades bringing most of the island of Britain under its control. By the 80s CE the southern half of the island, broadly modern England and Wales, had become the province of Britannia, but repeated campaigns into what is now Scotland never produced a lasting conquest, and the frontier eventually settled along the walls of the north.

Julius Caesar had led expeditions to Britain in 55 and 54 BCE without occupying it. For nearly a century afterwards Rome dealt with the British tribes, part of the wider Celtic world, through trade, tribute and friendly client kings. Augustus prepared invasions more than once but called them off, and the geographer Strabo argued that Britain yielded more through customs duties than conquest would bring. By the 40s CE the Catuvellauni had become the strongest power in the south-east, and their expansion drove Verica, king of the Atrebates and a Roman ally, into exile. His plight gave Rome a pretext.

Under the senator Aulus Plautius, an army of several legions crossed the Channel, probably landing at Richborough in Kent, though some historians propose the Solent. One legion, the Second Augusta, was commanded by the future emperor Vespasian. The British leaders Togodumnus and Caratacus confronted the invaders where they had to cross a river, usually placed on the Medway near Rochester, in a battle that lasted two days, then fell back across the Thames. Claudius then arrived in person for the advance on Camulodunum (Colchester), and a triumphal arch in Rome claimed he received the surrender of eleven British kings without loss.

Vespasian pushed west towards Exeter, while other forces moved north. By 47 CE Rome probably controlled the land south-east of a line from the Humber to the Severn, roughly the course of the Fosse Way. Caratacus continued to resist from Wales until he was defeated in about 50 CE; he fled to the Brigantes of northern England, whose queen Cartimandua handed him over. In 60 CE the governor Gaius Suetonius Paulinus attacked the island of Mona (Anglesey), a centre of the druids, but the Boudican revolt forced him back, and the rebels destroyed Colchester, London and St Albans before their defeat.

After a Brigantian civil war in 69 CE, Roman governors advanced into northern England, establishing forts such as Carlisle in the early 70s. Frontinus subdued the Silures of south Wales around 76 CE and founded the legionary base at Caerleon. Gnaeus Julius Agricola, governor from 78 CE and the subject of an admiring biography by his son-in-law Tacitus, completed the conquest of Wales and Anglesey and then campaigned deep into Scotland. In 84 CE he defeated the Caledonians under Calgacus at Mons Graupius.

Agricola was recalled in 84 CE and his northern gains were soon given up. Around 87 CE the frontier was drawn back to the Stanegate road between Carlisle and Corbridge. From about 122 CE Hadrian built his wall from the Tyne to the Solway. His successor Antoninus Pius pushed north again and built the Antonine Wall between the Forth and Clyde, but it was abandoned in 162 CE. Later expeditions, notably under Septimius Severus in 209 CE, penetrated far north without holding the land; Dio claimed Severus lost 50,000 men to guerrilla attacks.

Roman rule in Britain lasted until about 410 CE. Its forts, roads and towns, among them London, Colchester, Chester and Carlisle, left a deep mark on what is now the United Kingdom.

Our 1 BCE map shows Britain before the invasion, and our 100 CE and 200 CE maps show the Roman province with its northern frontier.