Socrates of Constantinople
Galla had three full-siblings. Her only brother was Valentinian II, first co-emperor with Gratian from 375 and then the only legitimate Western Roman Emperor from 383 to his death by hanging on 15 May 392. His death was officially reported as a suicide but Arbogast, his "magister militum", was suspected to have had a hand in it, an accusation found in the writings of Socrates of Constantinople, Orosius, and Zosimus. Sozomen was less certain and mentioned both versions of how Valentinian II died.