Like Valerian II, who was made the ward of Ingenuus, governor of the Illyrian provinces, Saloninus was put under the protection of the praetorian prefect Silvanus (otherwise named as Albanus).

However, Postumus's men took violent exception to this attempt to enforce the rights of the representative of a distant emperor who was manifestly failing in his duty to protect the Gallic provinces.

Gallienus, who was fully engaged elsewhere – probably campaigning on the middle Danube – could do nothing to save his son (by this time Saloninus's grandfather, the senior Emperor Valerian, was probably already a captive of the Persian King Shapur I).

Saloninus's troops, in their desperation, finally proclaimed him emperor, perhaps hoping that this would induce Postumus's army to desert him and join them in a bid for Empire – i.e., against Valerian and Gallienus.

Throughout the period of his sole reign, Gallienus made no effort to elevate his third son, Egnatius Marinianus, to the purple or associate him in any way with his government of the Empire – although he did allow him to be elected to the largely ceremonial office of Consul in 268.

[citation needed] Christopher Entwistle and Noël Adams have argued that a grey and white sardonyx kept in Munich that is generally thought to depict Philip II may actually be of Saloninus.