The Legio XXII Deiotariana, named after Deiotarus, a Celtic king of Galatia, was a legion in the Imperial Roman army. It was formed around 48 BC and ceased to exist or was annihilated during the Bar Kokhba revolt between 132–136 AD. Its emblem remains unknown.

Origin of the Legio XXII Deiotariana

Originating from the Celtic tribe of the Tolistobogii in Galatia, now modern Turkey, the legion was raised by Deiotarus, who became an ally of Pompey, a general of the Roman Republic, in 63 BC. Pompey appointed him king over all the Celtic tribes of Asia Minor, collectively known as Galatians. Deiotarus assembled an army of 12,000 infantry and 2,000 cavalry, trained with Roman assistance. This force was divided into thirty cohorts, equivalent to about three Roman legions, and supported Rome in the Third Mithridatic War against Mithridates VI of Pontus.

After Deiotarus’ troops suffered a significant defeat against Pharnaces II of Pontus near Nicopolis, the survivors formed a single legion that fought alongside Julius Caesar in his victorious campaign against Pontus, including the Battle of Zela in 47 BC.

Early history (BC) of the Legio XXII Deiotariana

Following the death of Amyntas in 25 BC, Galatia was absorbed into the Roman Empire, and the Galatian army was integrated as a Roman legion. A papyrus from 8 BC mentions two soldiers from this legion, suggesting its incorporation into the Roman army occurred between 16 BC and 8 BC. Assigned to Nicopolis near Alexandria in Egypt alongside III Cyrenaica, the legions protected the province, especially multicultural Alexandria.

In 26 BC, Aelius Gallus’ campaigns against Nubia and in search of Arabia Felix (Yemen) ended abruptly in 25 BC due to heavy troop losses. When Nubians, led by Queen Candace Amanirenas, advanced towards Elephantine in 23 BC, the Romans, now under Gaius Petronius, retaliated and sacked the Nubian capital Napata in 22 BC. The XXII likely participated in these conflicts.

Later history of the Legio XXII Deiotariana

Later, under Emperor Nero, the legion joined the campaign (55–63 AD) against the Parthian Empire, which had invaded the Roman-allied kingdom of Armenia. In 66 AD, during the Jewish revolt, a vexillatio (detachment) from the legion joined Vespasian’s forces in Judea.

The legion’s name was officially designated as Deiotariana under Trajan, although it had been unofficially used since Claudian times.

The last definite record of Legio XXII Deiotariana dates to 119 AD. By 145 AD, when a comprehensive list of legions was compiled, it was no longer mentioned, leaving its fate uncertain. It’s suggested the legion suffered heavily during Simon bar Kokhba’s Jewish rebellion. Although the connection to the Bar Kokhba revolt is debated, evidence from Caesarea Maritima, particularly an aqueduct repair inscription possibly mentioning the legion during 133-134 AD, suggests its last known location was in Judea. The erasure of the inscription might indicate a deliberate act of damnatio memoriae due to the legion’s defeat. However, there’s also a possibility that the inscription referred to another legion.

Was the Legio XXII Deiotariana ever in Britain?

Epigraphic Evidence for Legio XXII Deiotariana in Britain

The following inscription was found in Chester (Deva)

RIB 3163 - Fragmentary tombstone (before A.D. 161)

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• Latin
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This would appear to be part of the curriculum vitae of a commander of the Twentieth legion and if so does not prove that any part of Deiotarus’ legion was stationed in Britain, merely that a former ‘First Spear’ of the legion was later posted to the Chester fortress as Prefect of the Legio XX Valeria Victrix.

An alternative explanation?

Promotion from a primipilus to the rank of praefectus is, however, not normal. A centurion, even a ‘Top Gun’ primus pilus, would have come from among the lowest class of Roman citizens, the plebs, whereas a praefectus legionis would be recruited from among the upper echelons of Roman society and would traditionally have been a senator of praetorian status who had formerly served in the legions as a tribunus laticlavius.

The normal career path established during the Republic was:

• primipilus – ‘first spear’; the most experienced centurion in a Roman legion.
• praefectus castrorum – ‘prefect of the camp’; the most senior military rank a plebian Roman could hope to achieve. After serving in this capacity, the stipend allocated to him would have elevated the man during the Republic to equestrian status.
• tribunus militum – ‘military tribune’; open to anyone of equestrian rank, who would have started his career in command of a cohors peditata, the lowest type of peregrine auxiliary unit. The tribune would then perhaps have progressed to command a cohors equitata or a cohors milliaria before seeking employment in the Legions.
• tribunus angusticlavius – ‘legionary tribune with narrow stripe’; allocated five per legion; they were subservient to the single senatorial tribune.
• praefectus alae – ‘cavalry commander’; the cavalry alae were the most prestigious branch of the auxilia.

Beyond the rank of cavalry prefect an exceptional man may have gone on to become a senator, but this goal was achieved by few. Given this information it would appear that the most obvious expansion and translation of RIB 3163 is incorrect. However, the text can also be read:

‘The Praepositus of the Twenty-second Legion Deiotariana [and] the Prefect of the Twentieth Legion Valeria Victrix [have made this].’

Which perhaps indicates that a vexillatio of the Twenty-second under the command of a praepositus (literally ‘the man in charge’) was stationed at Chester together with the Twentieth.