Valentinian II was the son of Valentinian I and became emperor when his father died. He was still only a child at the time and the Western empire was divided between him and his half-brother Gratian. However, while Gratian ruled at his will, Valentinian was too young to rule and, instead, several behind-the-scenes characters exercised the real power on his behalf.
After Gratian's death Valentinian faced a major threat from Magnus Maximus who was gobbling up the Western empire and had no room for him in his quest. He solicited and then received help from Theodosius, the emperor of the East, who subsequently came to his aid and defeated Maximus. However, Valentinian was still unable to shake the web of control that others had over him. Theodosius lingered in Italy after the defeat of Maximus and essentially ruled the entire empire from Valentinian's own court while simultaneously relegating Valentinian to the background. When he finally left, he appointed one of his commanders, Arbogastes, as an administrative aide for Valentinian II.
This would be a thinly veiled puppet of Theodosius. Valentinian, not being the wiser, complained to Theodosius by correspondence about his situation and lack of empowerment. The complaints fell on deaf ears as this was, naturally, all part of Theodosius's plans. When he saw nothing would be done about the issue he summoned the courage to force Arbogastes to retire only to have the general tear up the resignation letter in his face. He then sneered and derided Valentinian with a comment to the effect that he wasn't taking orders fom him. In a fit of anger Valentinian grabbed a sword and started for Arbogastes but was held back by guards. Two days later he was found hung in a room. Whether he committed suicide in despair over his powerlessness or was assassinated directly on account of Arbogastes is left to speculation.
RIC 49c (Trier) Solidus Obv: DNVALENTINIANVSIVNPFAVG, pearl-diademed, draped and cuirassed bust right.
Rev: VICTORIAAVGG, Theodosius and Valentinian seated facing, together holding globe, Victory standing behind with wings spread. Lot sold for $700 1/16/02.
RIC 77a (Constantinople), Cohen 72 Siliqua Obv: DNVALENTINIANVSPFAVG - Diademed bust right, draped and cuirassed.
Rev: VOT/X/MVLT/XX - Legend in four lines within wreath. Lot sold for $154 12/23/01.
RIC 26b (Siscia), Cohen 22 AE2 Obv: DNVALENTINIANVSIVNPFAVG; diademed, draped, cuirassed bust right.
Rev: REPARATIOREIPVB; Emperor standing front, offering hand to kneeling woman on left and in left hand globe with Victory atop.
RIC 14b (Heraclea) AE3 Obv: DNVALENTINIANVSPFAVG - Diademed bust right, draped and cuirassed.
Rev: CONCORDIAAVGGG - Constantinopolis seated, head left, holding globe and spear. Lot sold for $27 3/10/02.
RIC 86a (Constantinople), Cohen 30 AE4 Obv: DNVALENTINIANVSIVNPFAVG; diademed, draped, cuirassed bust right.
Rev: SALVSREIPVBLICAE; Victory walking left, dragging barbarian captive.