The battle was short: in the morning of the same day the Byzantines decided to attack and the right Byzantine flank under Aplakes engaged the Bulgarians’ left. It managed to inflict casualties to the Bulgarian left flank and even push it back, but the Byzantine center and left did not engage in the battle, thus leaving Aplakes’ attack unsupported. When Krum saw the inaction among the Byzantine center and left he took action. Krum ordered a second line of Slavic infantry to engage Aplakes' contingent while a unit of Bulgar horse archers and heavy cavalry attacked the flanks of Aplakes' contingent from both sides. The Anatolian theme was the first to withdraw, followed by the entire army. The soldiers of Aplakes were left behind and most of them perished, including their commander. The battle took place in a valley and when the Bulgarians saw the retreating enemy which was in the higher positions they at first suspected a trap. In fact they also did not expect to achieve success so quickly and at first did not chase them. But when the Bulgarians were certain that the enemy was fleeing in panic, their heavy cavalry rushed after the Byzantines. Some of them perished during the flight, others hid in different fortresses some of which were taken by the Bulgarians and the rest managed to reach Constantinople. The chief commanders of the Byzantine army, including the Emperor Michael I Rangabe and Leo the Armenian, were the first to retreat from the battlefield. The Bulgarians took the Byzantine camp and a rich prize including gold and weaponry.