Answer
Yes, the surviving account of "Res gestae" ends with Emperor Valens' death. The "Res gestae" is an account of the reign of Emperor Valens, who was killed in the Battle of Adrianople in 378 AD. The surviving account of the "Res gestae" ends with Valens' death, as the author of the account, Ammianus Marcellinus, died shortly after Valens' death.