Evocatus

: evocati) was a soldier in the Ancient Roman army who had served out his time and obtained an honorable discharge (honesta missio) but had voluntarily enlisted again at the invitation of the consul or other commander.

[2] Evocati held a higher rank in the army than common legionary soldiers and are sometimes written of in conjunction with the equites Romani,[3] and sometimes classed with the centurions.

[4][5] Evocati appear to have been frequently promoted to the rank of centurion and were customarily entitled to bear the vine staff and discipline fellow soldiers.

Thus, Pompey induced a great many of the veterans who had served under him in former years to join his standard at the outbreak of the civil war, with the promise of rewards and the command of centuries.

The name evocati was also applied to a select body of young men of the equestrian order who were appointed by Emperor Domitian to guard his bedchamber.