Flavius Magnus Magnentius was proclaimed emperor in AD 350 at Autun. Having defeated and killed Constans, Magnentius gained allegiance of the West. However, Magnentius was not recognised by Constantius who tried to influence the Germans against him. To deal with the German threat, Magnentius appointed his brother Decentius as Caesar. When Magnentius suffered defeat in Pannonia, he withdrew to Italy and finally Gaul. In AD 353 he committed suicide at Lyons.

The above coin, struck in AD 353, is a prime example of Magnentius' propaganda, where the reverse displays a large christogram between an alpha and an omega - although a pagan, Magnentius tried to gain the support of the Catholics against the heretic Constantius.

The christogram, a monogram of the first two Greek letters of Christ's name, X (Chi) and P (rho) was placed by Constantine I on the shields of his soldiers after his victory at the Milvian bridge in AD 312 and it appears on Roman coinage from this time on. During the fifth century, from c. 420 on, the christogram appeared frequently on both Western and Byzantine coinage, the latter in particular displaying both the tall cross (which replaced the staff that was previously carried by Victory) and the christogram as Christian imagery. Under Theodosius II and Justinian I the image of a cross on a globe (globus cruciger) as attribute of the emperor on whom divine power was bestowed, was depicted on coin portraits of emperors.

Obv. Magnentius right, DN. MAGNENTIVS AVG.
Rev. Large christogram between A and W, SALVS DD. NN. AVG. ET CAES., in ex. AMB.