septimius had served under pompey in his eastern campaign in the 60s bc, and he was in the army with which aulus gabinius restored cleopatra's father ptolemy xii auletes to the throne in 55 bc. he had stayed in egypt as part of a mercenary garrison, known as the gabiniani, to support the king. in "commentarii de bello civili", caesar refers to him as a "military tribune".