Why did the Romans abandon Britain in AD 410?

Roman rule in Britain had properly started in AD 43 under Emperor Claudius, although, Julius Caesar had led earlier invasions in 55 and 54 BC, but did not stay.

Once Claudius' forces finally reinvaded, Rome's presence lasted for more than 350 years, and it relied on army bases, Roman-style towns, and systems of tax and law to maintain control.

However, by the late fourth century, the situation had changed. The empire itself was breaking apart because of repeated struggles for power and rising pressure on its borders.

In Britain, this created a dangerous gap, as the province had always depended on supplies and troops from the mainland. 

During the rule of Emperor Honorius, the western half of the Roman Empire was almost always in crisis.

In AD 401, the Visigoths invaded Italy under the leadership of Alaric. The response meant legions had to be moved from other places.

Troops were pulled out of Britain, weakening the local army. At the same time, Saxon raiders increased their attacks on the eastern and southern coasts of Britain, while Irish and Pictish raids grew worse in the north and west.

Without more troops, local defences were stretched too thin. 

Rebellion inside Britain made things worse. In the early fifth century, several rebel leaders in Britain tried to take imperial power.

One of the most important was Constantine III, who was declared emperor by British troops in AD 407.

He crossed into Gaul with a large force and took more soldiers from the island. His actions weakened Honorius’s control but failed to bring stability or restore order.

The imperial court was in Ravenna, a city increasingly under threat, and could not offer any real help. 

In this setting, the so-called “Rescript of Honorius” in AD 410 is often seen as the final break.

The emperor's message to the cities of Britain to take care of their own defence was not an official end to the province but a recognition of reality, which has usually been taken to show the end of Roman rule.

It could no longer keep control over the region. Britain was cut off from the political and military systems that had kept it going.

Roman officials either left or became part of local power groups, which meant that some Romano-British leaders probably tried to keep order.

However, there was no longer a central government able to deal with attacks or organise defence. 

The Romans leaving did not mean that all signs of Roman life vanished straight away, which allowed Roman culture, laws, and buildings to survive in some places.

However, the tax system collapsed, the army broke up, and central government fell apart, causing town life and trade links to fall quickly.

Britain entered a time often called sub-Roman, typified by divided rule, more local control, and increasing danger from outside attacks.

Within a hundred years, the first Anglo-Saxon kingdoms began to take the place of the old Roman system.