AE Follis (AE4), A.D. 423-425, Rome, 12.0mm, 1.06g, 0°, RIC X 1916, very rare.
Obv: D N IOHANN-ES P F AVG. diademed, draped, and cuirassed bust right.
Rev: SALVS REI-PVBL[ICE]. Victory advancing left, holding trophy and dragging captive; Christogram to left.
--------------------------------------------------
Ioannes, or Johannes, was a usurper against Valentinian III and Roman Emperor in the west from 423-425. On the death of the Emperor Honorius (August 15, 423), Theodosius II, the remaining ruler of the House of Theodosius hesitated in announcing his uncle's death and in the interim Honorius's patrician, Castinus, elevated Johannes as Emperor. The events of Johannes' reign are not entirely clear; Johannes was proclaimed at Rome and praetorian games were held in his honor. There is a mention of an expedition against Africa, but its fate, presumed unsuccessful.

Johannes had hoped that he could come to an agreement with the eastern Emperor Theodosius II, but when Theodosius elevated the young Valentinian III first to Caesar, then to co-emperor as an Augustus (undoubtedly influenced by Valentinian's mother Galla Placidia), he knew he could only expect war. Johannes moved his base of operations to Ravenna, knowing full well that the Eastern Empire would strike from that direction. The army of the eastern Empire left Thessalonica for Italy, and soon made their base in Aquileia. Primary sources state that Ravenna fell to an assault by Theodosius' forces. It is also possible that the garrison betrayed the city, along with Johannes. In any event, The fallen emperor was brought to Aquileia where first his hand was cut off, then he was paraded on a donkey in the Hippodrome to the insults of the populace, then after further insults and injuries he was decapitated in June or July 425.