GIUSTINA, ROMAN EMPRESS. - Daughter of Giusto, consular official of Picenum and relative of Magnenzio, whom she married while still a girl. Having been widowed, about 370 she married Valentiniano I, by whom she had four children. Upon her husband’s death (Nov. 373), she had her own son Valentiniano II proclaimed emperor together with Graziano; with him she resided at Sirmio until the death of Graziano (Aug. 383). Having come to Italy, she openly revealed herself for what she was, an intriguer, directing her son’s policy.
An avowed supporter of Arianism, she engaged in a struggle against St. Ambrogio, demanding that the bishop surrender a basilica to the heretics. Ambrogio refused, and G. attempted to have him arrested and driven into exile, but the people rose up in defense of their bishop. The Empress, enraged, responded with harsh repressions (385). Ever more hardened in her tyrannical arrogance, in Jan. 386 she had an edict promulgated against St. Ambrogio and the Catholics, imposing the decisions of the Arian Council of Rimini and threatening the death penalty against disturbers of religious peace. The following year, however, matters changed radically: the usurper Massimo was threatening to occupy Italy, posing as the defender of orthodoxy; G. became frightened and, to avert the danger, begged St. Ambrogio himself to go as ambassador to Massimo. Forgetting every injury, the holy bishop undertook the arduous task. The mission was unsuccessful, and in 387 Massimo occupied Italy. G., together with her son Valentiniano, fled to Tessalonica, seeking asylum with Teodosio. She appears to have died in 388.