He expected them to be unopposed; but the Persian general, having rallied his force and augmented it by fresh recruits, had returned towards the frontier, and, hearing of the danger of Arzanene, had flown to its defence.

Philippicus was taken by surprise, compelled to raise the siege of Chlomaron, and to fall back in disorder.

The Persians pressed on his retreat, crossed the Nymphius after him, and did not desist from the pursuit until the imperial general threw himself with his shattered army into the strong fortress of Amida.

Disgusted and discredited by his ill-success, Philippicus gave over the active prosecution of the war to Heraclius, and, remaining at head-quarters, contented himself with a general supervision.
Heraclius, on receiving his appointment, is said to have at once assumed the offensive, and to have led an army, consisting chiefly or entirely of infantry, into Persian territory, which devastated the country on both sides of the Tigris, and rejoined Philippicus, without having suffered any disaster, before the winter.

Philippicus was encouraged by the success of his lieutenant to continue him in command for another year; but, through prudence or jealousy, he was induced to intrust a portion only of the troops to his care, while he assigned to others the supreme authority over no less than one third of the Roman army.