Editing Theodosius I (section)

=== Civil war: 387–388 ===
The peace with Magnus Maximus was broken in 387, and Valentinian escaped to the east with Justina, reaching Thessalonica ([[Thessaloniki]]) in summer or autumn 387 and appealing to Theodosius for aid; Valentinian II's sister [[Galla (wife of Theodosius I)|Galla]] was then married to the eastern emperor at Thessalonica in late autumn.{{Sfn|Kienast|pp=321–322|loc="Valentinianus II"}}{{Sfn|Kienast|pp=323–326|loc="Theodosius I"}} Theodosius may still have been in Thessalonica when he celebrated his ''decennalia'' on 19 January 388.{{Sfn|Kienast|pp=323–326|loc="Theodosius I"}} Theodosius was consul for the second time in 388.{{Sfn|Kienast|pp=323–326|loc="Theodosius I"}} Galla and Theodosius's first child, a son named Gratian, was born in 388 or 389.{{Sfn|Kienast|pp=323–326|loc="Theodosius I"}} In summer 388, Theodosius recovered Italy from Magnus Maximus for Valentinian, and in June, the meeting of Christians deemed heretics was banned by Valentinian.{{Sfn|Kienast|pp=321–322|loc="Valentinianus II"}}{{Sfn|Kienast|pp=323–326|loc="Theodosius I"}}

The armies of Theodosius and Maximus fought at the [[Battle of Poetovio]] in 388, which saw Maximus defeated. On 28 August 388 Maximus was executed.{{sfn|Williams|Friell| 1995|p=64}} Now the ''de facto'' ruler of the Western empire as well, Theodosius celebrated his victory in Rome on 13 June 389 and stayed in [[Milan]] until 391, installing his own loyalists in senior positions including the new ''[[magister militum]]'' of the West, the Frankish general [[Arbogast (magister militum)|Arbogast]].{{sfn|Williams|Friell|1995|p=64}} According to the ''Consularia Constantinopolitana'', Arbogast killed [[Flavius Victor]] ({{Reign|384|388}}), Magnus Maximus's young son and co-emperor, in Gaul in August/September that year. ''[[damnatio memoriae]]'' was pronounced against them, and inscriptions naming them were erased.{{Sfn|Kienast|pp=323–326|loc="Theodosius I"}}