By capturing central Syria, the Muslims had given a decisive blow to the Byzantines. The communication between Northern Syria and Palestine was now cut off. Abu Ubaidah decided to march to Fahl, which is about 150 metres (500 ft) below sea level, where a strong Byzantine garrison and survivors of the Battle of Ajnadayn were present. The region was crucial because from here the Byzantine army could strike eastwards and cut Muslim communications with Arabia. Moreover, with this large garrison at their rear Palestine could not be invaded.