Theodosius I (11 January 347 – 17 January 395), also called Theodosius the Great, was Roman emperor from 379 to 395. He was a general in the Roman army and the son of another general, Theodosius the Elder. When the emperor Valens died in battle fighting the Goths, Valens' nephew, the emperor Gratian, made Theodosius emperor. Theodosius married Gratian's sister. While emperor, Theodosius overcame three civil wars in the empire. Gratian and his brother the emperor Valentinian II both died young, and Theodosius made his own sons Arcadius and Honorius emperors. Theodosius made Christianity the official state religion of the Roman Empire and made other religions illegal.