Legio II Parthica

Legio secunda Parthica (Second Parthian legion) was a Roman legion levied by Emperor Septimius Severus in 197, for his campaign against the Parthian Empire, hence the cognomen Parthica. The legion was still active in the beginning of the 5th century. The legion's symbol were a bull and centaur.

Parthian campaign and Castra Albana (197-4th century)
Together with its twin legions I Parthica and III Parthica, the Second Parthian legion was levied for the attack on the eastern frontier. The campaign was a success and Ctesiphon, the Parthian capital was taken and sacked. After this war, II Parthica returned to Italia, and was stationed near Rome, in Castra Albana (Albano Laziale) – it was the first legion stationed in Italia in the last two centuries. Since it was not garrisoning a Roman province, they 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. Emperors in the 3rd century were very likely to have problems with usurpers, and Severus, by stationing the II Parthica near the capital, was aware of it.

Nevertheless, the legion served in the Severan campaign in Britain of 208–211 and afterwards, under Caracalla against the Germanic tribe of the Alamanni in 213. Next, the legion was again sent to Parthia and their commander Macrinus was responsible for Caracalla's murder in that region in 217. In the following year, however, the II Parthica, stationed in Apamea (Syria), abandoned Macrinus and sided with Elagabalus; the Second supported Elagabalus' rise to purple, defeating Macrinus in the Battle of Antioch. The new emperor awarded the legion with the cognomina Pia Fidelis Felix Aeterna (forever faithful, loyal and pious).

In 231, the legion fought under Alexander Severus against the Sassanid Empire, and returned with the emperor to the German provinces. It was at Moguntiacum (modern Mainz), when Alexander was assassinated in 235. In the following fight for the power, the II Parthica sided with Maximinus Thrax. In 238, the Roman senate declared Maximinus persona non grata and nominated Gordian III as emperor. Maximinus then marched on Rome to fight for his rights, taking the II Parthica, among other legions, with him. What happened next is a good example of the political power of the legions in the 3rd century. The II Parthica weighted the chances of its commander and, concluding that supporting him was not a good move, they killed Maximinus before he could harass the senate. As a reward, they were pardoned for supporting a public enemy and allowed to return to their camp in the Alban mountains.

In the next decades they were used as reinforcements in several provinces within the empire and continued to be used as pawns in the constant battles for the imperial throne of the 3rd century. Emperor Gallienus (253-260) awarded the legion with the titles V Fidelis V Pia and VI Fidelis VI Pia (respectively, "Five" and "Six times loyal and faithful").

Where the legion was based when it received these titles from Gallienus is uncertain. Other things being equal one would have thought that Valerian 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 by King Saporof the Persians at Edessa in 260. If so, it evidently survived that disaster as a functioning unit, and avoided the subsequent pit-falls of over-identification with the rebellion of the Macrianii and Palmyra's bid for autonomy under Zenobia.

It is possible that it would have returned to Europe as part of the army of the Macrianii and was forgiven by Gallienus after the latter were defeated. Unfortunately there is no evidence for its fortunes in this period.

In Mesopotamia
At the beginning of the 4th century, II Parthica had abandoned Italy. The legion was on the Tigris frontier in the middle of the 4th century, just before a major Roman defeat by the Persians in Singara, Mesopotamia. In 360, the Sassanid King Shapur II attacked and conquered the Roman fortified city of Bezabde (modern Cizre, in Turkey), which was defended by II Partica, II Armeniaca and II Flavia Virtutis. According Notitia Dignitatum, II Parthica was in Cepha, Turkey, around 400, under the command of the Dux Mesopotamiae.