In which year did the Roman army leave Britain to defend other parts of the Roman Empire, never to return again?

Alright, let's talk about the end of Roman Britain. The Roman Empire, which had controlled Britain for nearly 400 years, started experiencing serious problems in the early 5th century. The Empire was under pressure from invading tribes in Europe, and they needed to pull their legions back to defend the heart of the Empire, particularly Rome itself. So, in 410 AD, Emperor Honorius sent a letter to the cities of Britain essentially telling them they had to look to their own defenses. This date marks the official end of Roman rule, because the Roman army never returned to re-establish control. While Roman influence lingered for a while, with infrastructure and cultural practices remaining, 410 AD is the key year because it signifies the end of Roman military and political control. The other dates are incorrect because the Roman presence was very strong in Britain during those earlier centuries.