Answer
The death of Valens was chronicled in the "Res gestae", a Latin historical text written by Ammianus Marcellinus. Valens was a Roman emperor who ruled from 364 to 378. He was killed in the Battle of Adrianople, which was fought between the Roman Empire and the Visigoths. The "Res gestae" is a valuable source of information about the reign of Valens and the Battle of Adrianople.