), one of the guardians of the Egyptian king Ptolemy Dionysus, and commander of the troops, when Pompey fled to Egypt, B. C. 48.
He is called by Caesar a man of extraordinary daring, and it was he and L. Septimius who killed Pompey. (Case. B. C. 3.104; Liv. Epit. 104
; D. C. 42.4
He subsequently joined the ennuch Pothinus in resisting Caesar, and having had the command of the whole army entrusted to him by Pothinus, he marched against Alexandria with 20,000 foot and 2000 horse. Caesar, who was at Alexandria, had not sufficient forces to oppose him, and sent ambassadors to treat with him, but these Achillas murdered to remove all hopes of reconciliation.
He then marched into Alexandria and obtained possession of the greatest part of the city. Meanwhile, however, Arsinoe, the younger sister of Ptolemy, escaped from Caesar and joined Achillas; but dissensions breaking out between them, she had Achillas put to death by Ganymedes a eunuch, B. C. 47, to whom she then entrusted the command of the forces. (Caes. Civ. 3.108
; B. Alex.
4; D. C. 42.36
; Lucan 10.519