Cohors prima Aquitanorum (“1st Cohort of Aquitani”) was a Roman auxiliary infantry regiment. This auxiliary infantry regiment was originally recruited from among the Aquitanian tribes inhabiting the Bassin Aquitain, the Guyenne, and the Gascogne regions of south-western France. They were initially recruiited in the reign of founder-emperor Augustus after the revolt of the Aquitani was suppressed in 26 BC. Their capital town was Burdigala on the Garumna Fluvius, now known as Bordeaux on the lower Garonne. Unlike most Gauls, the Aquitani were not Celtic-speaking but spoke Aquitanian, a now extinct non Indo-European language closely related to Basque.
The regiment had a nominal strength of five-hundred foot soldiers.
The regiment was probably stationed on the Rhine frontier from an early stage. It first appears in the datable epigraphic record in 82 AD in Germania. The regiment is first attested in Britannia in 122, probably transferred to the island along with several other regiments to help in the construction of Hadrian’s Wall (122-32). They are thought to have formed the original garrison of the Carrawburgh fort on Hadrian’s Wall in Northumberland.
The regiment were withdrawn to the Pennines in the mid-second century, where the small size of their garrison fort at Brough on Noe suggests that as little as half the unit was actually stationed there and, this being the case, it is possible that another detachment of this unit may have been stationed at the, as yet undiscovered, fort sited nearby at Bakewell.
The regiment remained in Britain into the 4th century, as it left an inscription in the Saxon Shore fort of Branodunum (Brancaster, Norfolk) overlooking the Metaris Aestuarium on north-western coast of Norfolk. They ended up in the Saxon Shore fort of Branodunum.
There may have been two infantry cohortes called I Aquitanorum. A regiment of that name is repeatedly attested both in Germania Superior and Britannia. The regimane may wither have been split in two, the german one carrying the title veterana or they were a single unit, which alternated between the two provinces, although this was unusual for auxiliary regiments. None of the British inscriptions carry the title veterana, whereas several of the German ones do, and so appears more likely that they were separate units.
The regiments is attested in the following Roman forts in Britain: Bakewell, Brancaster (4th century), Brough-on-Noe (158), Carrawburgh.
Evidence for the presence of Cohors Primae Aquitanorum in Britain
Bakewell: The inscription (RIB 278) was found here.
RIB 278 - Altar dedicated to Mars Braciaca
To the god Mars Braciaca, Quintus Sittius Caecilianus, prefect of the First Cohort of Aquitanians, fulfilled his vow.
CAECILIAN PRAEF COH
Brocolitia (Carrawburgh): The inscription (RIB 1550) was found here.
RIB 1550 - Inscription
… under …]verus as emperor’s propraetorian legate the First Cohort of Aquitanians built this under … Nepos, the prefect.
[...  ]R COH I AQVIT
Navio ( Brough-on-Noe ): The inscription (RIB 283) was found here.
RIB 283 - Building dedication to Antoninus Pius
For the Emperor Caesar Titus Aelius Hadrianus Antoninus Augustus Pius, father of his country, the First Cohort of Aquitanians under Julius Verus, emperor’s propraetorian legate, under the charge of Capitonius Priscus, prefect, (built this).
[...]TONINO AV[  ...]
COH I AQVITAN[...]
SVB IVLIO V[...] AVG
PR PR INST[...]E
[...]APITONI[  ...]SCO PRAE
Branodunum (Brancaster): Tiles with the unity’s stamps on it were found at Brancaster. (Britannia vi (1975) p.288, no.25; stamped tile).
Burn 100; CIL XVI.65; military diploma, dated: July 17th 122AD.Military Diplomata (124AD) (RIB 2401.6)
L’Année Épigraphique 1997.1779b; diploma, dated c.126AD.