Excerpts from Books and Wikipedia
"The battle fought outside Adrianople in 378 revealed the inability of the Roman Empire to control the influx of 'barbarian' peoples into its territory. . . . In 376 some two million Germanic Visigoths and Ostrogoths had crossed the frontier into the empire west of the Black Sea. Unhappy with the treatment they received from the Roman authorities, these immigrants soon went on the rampage. . . . Some 40,000 men, approximately two-thirds of the Roman force, were slaughtered. The body of Valens was never recovered." [1001 Days]