His movements, however, were detected when the Byzantines' Arab "foederati" captured a few of his men, allowing Philippicus to counter his forces. This early warning was of particular importance since Kardarigan intended to attack on Sunday, a day of rest for the Christian Byzantines. Both armies appear to have been composed exclusively of cavalry, comprising a mix of lancers and horse-archers, possibly with a few cataphract units included. When Philippicus' scouts reported the Persians' approach, he positioned his men on elevated ground facing the direction from which the Persian army advanced, with his left flank protected by the foothills of Mount Izalas. The Byzantines appear to have been arranged in a single battle line with three divisions. The left division was commanded by Eiliphredas, the "dux" of Phoenice Libanensis, and included a Hunnic contingent of horse-archers under Apsich. The centre was commanded by the general Heraclius the Elder, later Exarch of Africa and father of future Emperor Heraclius (r. 610–641), while the right wing was commanded by the "taxiarchos" Vitalius. This arrangement was also adopted by the Persians as soon as they came into view of the Byzantine army. On the Persian side, the right division was under Mebodes, the centre under Kardarigan himself, and the left wing under Kardarigan's nephew, Aphraates. Unlike the Persian general, Philippicus remained with a small force at some distance behind the main battle line, directing the battle. After a short halt to leave their baggage train behind and form a battle line the Persian army quickly advanced on the Byzantines, shooting arrows as they approached. The Byzantines responded in kind and then sallied forth to meet the oncoming enemy. On the Byzantine right Vitalius was quickly victorious, his heavy cavalry breaking through the Persian flank and pushing his opponents to the left behind their own main line. At this point, however, disaster threatened as many of Vitalius' troopers broke formation and headed towards the enemy camp, intending to loot it. Philippicus, however, saw what had happened and reacted quickly. He gave his distinctive helmet to one of his bodyguards, Theodore Ilibinus, and sent him to rally the cavalry on pain of punishment by the army commander himself. The ruse worked: the men recognized the helmet and returned to order just in time to stop the Persians, who had regrouped in the centre and were pushing the numerically inferior Byzantines back.