DN VALENTINIANVS PF AVG, diademed, draped, & cuirassed bust right / GLORIA REIPVBLICAE, campgate with two turrets. 13mm, 1.25 grams. Thessalonica mint (?), minted 384-388 AD. 

Valentinian II (371–392 AD) was a Roman emperor of the Western Empire, proclaimed emperor at the age of four following the death of his father, Valentinian I, in 375. For much of his reign, real power was exercised by his mother Justina and later by powerful generals and senior emperors, particularly Theodosius I. After being driven from Italy by the usurper Magnus Maximus in 387, he was restored to his throne by Theodosius. In his later years he came under the influence of the general Arbogast, with whom he developed a tense relationship. Valentinian II died under suspicious circumstances in 392, possibly by suicide or murder, and his death helped trigger the civil war that ultimately confirmed Theodosius I as sole ruler of the Roman Empire.