Flavius Gratianus, son of Valentinian I, was proclaimed Augustus at the age of eight (AD 367) and ruled since AD 375. Gratian was in control of the West and defeated the Alemanni. In AD 383, when Magnus Maximus rebelled against Gratian, his own soldiers deserted him and he was killed in Gaul. The coin above was struck at Constantinople and bears the very common reverse legend securitas reipublicae for AE3 coinage of Gratian. AE3 coinage of Valentinian usually featured gloria Romanorum as reverse legend.

Obv. Diademed Gratian right, D. N. GRATIANVS P. F. AVG.
Rev. Victory advancing, holding wreath, SECVRITAS REIPVBLICAE.