But we should not forget the gruesome business of fighting itself, where another key to Roman success is to be found. Battles were not fought for their own sake. The object was not to demonstrate Roman superiority. They were not mere tests of courage and manhood. Some thirty years earlier the Emperor Maurice had reminded his generals in the field that the aim was to win at minimal risk and minimal cost. Engagements were, therefore, only to be fought when the enemy had been manoeuvred into a losing position. The battle itself was but a transition between a phase of ordered movement of two opposing forces and a phase in which the defeated side, disordered, dispersing in flight, was an easy prey for the victors. The prime duty of the victorious Roman commander was to extract every possible military advantage from the second phase. A relentless pursuit was to be sustained. As many as possible of the enemy troops were to be hunted down and killed. As much damage as possible was to be inflicted on their fighting capability by diminishing their numbers and by scattering such units as still functioned far and wide. Regular references to the dispersal and prolonged pursuit of defeated Persian forces indicate that Heraclius was following these precepts and was seeking, at every available opportunity, to chip away at Persian fighting strength as well as Persian morale.

— The Last Great War of Antiquity by James Howard-Johnston (Page 244)