Sebastianus (Greek: Σεβαστιανός; died 9 August 378) was a Roman general who died at theBattle of Adrianople alongside the EmperorValens during theGothic War.
Sebastianus is first mentioned as theduxAegypti, serving around 356–358. He supportedGeorge of Cappadocia and hisArian supporters againstAthanasius of Alexandria, expelling the supporters of Athanasius from the churches ofAlexandria on 24 December 358.[1] Athanasius, in his own account of the events, attributes this to Sebastianus being aManichee.[2] While in Egypt, he also received a visit fromLibanius.
From 363 to 378, Sebastianus served ascomes rei militaris, initially under the emperorJulian. Accompanying the emperor onJulian's Persian expedition against theSasanian Empire, Julian gave Sebastianus a joint command withProcopius, with 30,000 to initially hold theTigris before, if possible, joining KingArsaces II of Armenia and march southward, to reach Julian's army in Assyria.[3]
Returning with the defeated army after the death of Julian, he probably accompaniedValentinian I to the western provinces in 364. In 368, while commanding the Illyrian and Italian armies, he was summoned by Valentinian to assist in the campaign against theAlemanni. Then in 375, Sebastianus was sent by Valentinian to aid themagister peditumMerobaudes in conducting some raids against theQuadi. When news of the emperor's death reached Merobaudes, he sent Sebastianus, who was unaware of Valentinian's death, to a distant posting to ensure that Sebastianus could not use his popularity with the troops to interfere with Merobaudes' plans for the succession, mitigating the risk that Sebastianus might possibly be raised by the troops to the rank ofAugustus.[1]
Sometime in 378, either through his own volition or through the intrigues of the imperial court eunuchs in the west, Sebastianus resigned his commission and travelled to the court ofValens atConstantinople. There, he was asked by the emperor for help in theGothic War, appointing him to the post ofmagister peditum in the process.[1] Gathering together a select band of infantry and cavalry, under Sebastianus' leadership the Romans wrested back some of the initiative by conducting a successful semi-guerilla type campaign against the Goths, with Sebastianus operating primarily inThrace. As a result of his successful encounters, he forced the Gothic leaderFritigern to withdraw. However, his boasting of his military exploits encouraged Valens to seek a military encounter where the emperor would win a victory over the Goths. In the subsequent council of war, he was the principal officer who advised Valens not to wait until the forces of the EmperorGratian arrived before bringing the Goths to a battle.[4] Accompanying the emperor, he perished along with Valens in theBattle of Adrianople.[5][6][7]
He was described byAmmianus Marcellinus as "a quiet and peace-loving man"[8] and "a general of well-known vigilance",[9] while he was praised byEunapius for his military abilities and his contempt for wealth.[10] Nothing is known about his family apart from the death of his wife in 357.[10]