Which of the following battles is often considered as marking the beginning of the fall of the Western Roman Empire?

The story behind the answer

Battle of Adrianople (378 CE) is often seen as the turning point toward Rome’s fall because the Visigoths annihilated a major Roman field army and killed Emperor Valens. The defeat shattered the aura of Roman military invincibility, forced the empire to rely more on barbarian federate troops, and opened the Balkans to Gothic settlement—setting the stage for Alaric’s rise and the Sack of Rome in 410.

By contrast, Pollentia (402) was a temporary Roman victory under Stilicho, Thessalonica’s clashes were inconclusive, and Constantinople withstood sieges. Remember it this way: “A for Adrianople, A for Annihilation (of a Roman army) and the Aftermath that led to Alaric.”