Since it was not garrisoning a Roman province, it functioned both as a reserve that could be used in afflicted parts of the Empire, as well as a security element against possible internal rebellions.

The new emperor awarded the legion with the cognomina Pia Fidelis Felix Aeterna (forever faithful, loyal and pious).

Maximinus then marched on Rome to fight for his rights, taking the II Parthica, among other legions, with him to be stationed again at Castra Albana.

The II Parthica weighed the chances of its commander and, concluding that supporting him was not a good move, they killed Maximinus before he could harass the senate.

Other things being equal one would have thought that Valerian, father and co-regent with Gallienus, would have wanted to take it to the east with him in the late 250s and that it would have been involved in his defeat and capture by King Sapor of the Persians at Edessa in 260.

Besides an inscription from Macedonia giving thanks to the god Jupiter for the safety and well-being, "pro salute et incolumitate," of Gallienus, and an inscription from Rome dating to AD 242 giving thanks to the legion's "Genius Gordiana and to Fortuna" for keeping safe emperor Gordian and his spouse, there is little known regarding its fortunes in this period.