Roman Emperor - Valens
Valens was Roman emperor in the East from 364 A.D. to 378 A.D. Born Pannonia (now part of central Europe), about 328 A.D.
Valens was named co-ruler by his brother Valentinian I. He subdued the revolt of Procopius (366) and from 372 to 376 he conducted intermittent war against the Persians. From 367 to 369 A.D., Valens fought the Visigoths successfully, but in 376 A.D. he permitted them to cross the Danube River and to settle in Roman territory. Alleging harsh treatment by Roman officials, the Visigoths rebelled.
In 378 AD, the legions of Valens, confronted by the heavy cavalry of barbarian hordes at Adrianople, met with heavy defeat. He and most of his legions were destroyed, leaving Rome's eastern frontiers defenseless.
Valens died at Adrianople in Thrace, August 9, 378.
The Romans were, thereafter, forced to use Gothic horse soldiers as mercenaries to maintain the Empire. For centuries heavy cavalry were to dominate the tactics of war.