Legio IIII Italica: one of the legions of the later Roman empire. Its name suggests that Roman citizens from Italy were among the first recruits.
This legion is only known from a text known as Notitia Dignitatum, a list of Roman officials and army units that existed in the last decade of the fourth century. It belonged to the field army of the Orient, but the legion must have been created as garrison of a province.
The creation of the Fourth Italian legion cannot be dated, but must be in the first half of the third century, because after c.250 Italy was no longer associated with the best part of the empire. The emperor Severus Alexander (r.222-235) is the most likely creator of this unit, and the future emperor Maximinus Thrax may have been among its first officers.note[Cf. Historia Augusta, Maximinus 5.5.]
Severus Alexander may have needed this unit during his campaign against the Sasanian empire in Persia (after 230) and may have taken it with him to Mainz, where it may or may not have taken part in the rebellion that made Maximinus emperor.
This unit was, as the reference in the Notitia Dignitatum proves, in c.400 in the eastern half of the empire.