The Twenty-Second Firstborn Legion (and its twin XV Primigenia) was founded by the emperor Caligula in 39, who needed extra forces for his campaigns in Germania, the Legion was probably recruited in the eastern recruiting grounds of the existing 22nd Deiotariana Legion, the eagle emblem of which it also adopted. The emblems of the Twenty-second were the demigod Hercules and the Capricorn. The 22nd Primigeneia was possibly given its title by the next emperor, Claudius, for the goddess Fortuna Primigeneia was his patron deity.
The 22nd Primigeneia had just two permanent bases throughout its career. The legion was based at Mogontiacum (Mainz), for the next thirty years, sending troops to Italy to help install their commander-in-chief, Vitellius, as emperor. Those cohorts of the 22nd Primigeneia that remained on the Rhine surrendered to Civilis and his rebels in AD 70. Vespasian subsequently transferred them down the Rhine to Vetera, where, for their penance, they built a new base to replace the one destroyed by the rebels.
We know that XXII Primigenia still existed at the beginning of the fourth century, because it received the honorific title “Primigenia CV”, which must mean Constantiana Victrix”, but after the reign of Constantine I the Great (306-337), it disappears from our sources.
Epigraphic Evidence for Legio XXII Primigenia in Britain
Evidence from RIB1026 (see below) suggests that a vexillation from leg. XXII Primigenia sent to Britain in the early third century.
RIB 1026 - Funerary inscription for Gracilis (c. A.D. 217)
To the spirits of the departed (and) to … Gracilis, centurion from Upper Germany from the Twenty-Second Legion: Aurelia […]illa had this set up to her husband.
[...]G XXII AVRELIA
RIB 3163 - Fragmentary tombstone (before A.D. 161)
… primus pilus of the Twenty-Second Legion Deiotariana, prefect of the Twentieth Legion Valeria Victrix.
[..] ▸ LEG ▸ XXII D[...]
[..]AEF ▸ LEG ▸ XX ▸ V ▸ V
RIB 2216 - Bulding inscription of the Twenty-Second Legion Primigenia
A detachment of the Twenty-Second Legion Primigenia (built this).
Evidence from Inscriptiones Latinae Selectae(ILS) for Legio XXII Primigenia in Britain
T PONTIVS T F PAL SABINVS PRAEF COH I PANN ET DALMAT EQ C R TRIB MIL LEG VI FERRAT DONIS DONATVS EXPEDITIONE PARTHICA A DIVO TRAIANO HASTA PVRA VEXILLO CORONA MVRALI > LEG XXII PRIMIG > LEG XIII GEMIN PRIMVS PILVS LEG III AVG PRAEPOSITVS VEXILLATIONIBVS MILLIARIIS TRIBVS EXPEDITIONE BRITTANNICA LEG VII GEMIN VIII AVG XXII PRIMIG TRIB COH III VIG COH XIIII VRB COH II PRAET P P II PROC PROVINC NARBONENS IIII VIR I D QVINQ FLAMEN PATRON MVNICIPI
M. Maenio C. f. Cor. Agrip|pae L. Tusidio Campestri1, | hos- piti divi Hadriani, patri | senatoris, praef. coh. II Fl. | Britton. equitat3, electo | a divo Hadriano et misso | in expeditionem Britan|nicam, trib. coh. I Hispanor. | equitat3, praef. alac | Gallor. et Pannonior. catafracta|tae, proc. Aug. praef. classis | Brittannicae, proc. provinjciae Brittanniae, equo pu|blico, patrono municipi, | vicani Censorglacenses4 | consecuti ab in- dulgentia | optimi maximique imp. Anto|nini Aug. Pii beneficio inter|pre- tationis eius privilegia, quibus in p[e]rpetuum aucti | confirmatique sunt. | L. d. d. d.