Khalid, sensing Heraclius's plan, feared that the Muslim armies would be isolated and destroyed. In a council of war he suggested that Abu Ubaidah draw all the Muslim armies to one place so as to fight a decisive battle with the Byzantines. As per Khalid's suggestion, Abu Ubaidah ordered all the Muslim armies in Syria to evacuate the conquered land and concentrate at Jabiya. This maneuver gave a decisive blow to the Heraclius's plan, as he did not wish engage his troops in an open battle with the Muslims, where the light cavalry could be effectively used. From Jabiya, on Khalid's suggestion, Abu Ubaidah ordered the Muslim army to withdraw on the plain of the Yarmouk River, where cavalry could be used. While the Muslim armies were gathering at Yarmouk, Khalid intercepted and routed the Byzantine advance guard. This was to ensure the safe retreat of the Muslims from conquered land.