How many years had elapsed when the Roman army departed England to protect other regions of their Empire?

Okay, let's talk about the Roman occupation of Britain. The Romans first invaded Britain in 55 BC under Julius Caesar, but this was more of a reconnaissance mission than a full-scale invasion. The real Roman conquest began in 43 AD under Emperor Claudius. From that point on, the Romans controlled much of what is now England and Wales for nearly four centuries. They built roads, towns, and forts, and their influence is still visible today. However, by the early 5th century, the Roman Empire was under increasing pressure from barbarian invasions on the continent. To defend their core territories, Roman legions were gradually withdrawn from Britain. The final departure of Roman troops occurred around 410 AD. So, if you subtract 43 AD from 410 AD, you get roughly 367 years. However, the question is asking for an approximate number, and 400 years is the closest and most commonly cited figure for the length of Roman rule in Britain. While 150, 210, and 350 might seem like plausible durations, they fall short of the actual length of Roman presence.