Legio XXII Primigenia, was levied by emperor Caligula in 39, for his campaigns in Germania. There are still records of the XXII Primigenia in Mainz in the end of 3rd century AD. The legion's symbols were a Capricorn and the god Hercules.

The XXII Primigenia was first stationed in Moguntiacum (modern Mainz) in the Roman province of Germania Superior, guarding the Rhine border as part of the limes. Along with the rest of the Germanic army, the legion supported Vitellius in the Year of the four emperors (69 AD). During the Batavian rebellion, the XXII Primigenia, commanded by Gaius Dillius Vocula, was the only Germanic legion that survived attacks of the rebels and stayed in its camp, defending Mainz. They remained in Mainz until at least the 3rd century. Future emperor Hadrian was one of its commanders in 97-98 AD.

The Rhine settlement was their main camp, but subunits of the legion participated in the building of the Antonine wall in Scotland (2nd century) and in the campaigns against the Sassanid empire (around 235 AD).

They were still in Mainz during the attack of the tribe of the Alamanni in 235 and were responsible for the lynching of emperor Severus Alexander, when he tried to negotiate with the enemy.

In 269, Laelianus, the commander of the legion, became emperor of the Gallic empire.

See also: List of Roman legions, Roman legion