After strenuous effort, Emperor Heraclius assembled a large army, under the Commander-in-chief Theodorus at Antioch, from various regions of his empire, to take a decisive stand against the Muslims and to rid his domain of the desert vermin. In the face of this massive threat and with no prospect of reinforcement from Madinah,, Khalid ibn al-Walid withdrew south to the bank of River Yarmuk, an eastern tributary of river Jordan, a few miles .south to the Sea of Galilee.
He abandoned even Damascus order to secure a strategic position. The Byzantine army, though very large, suffered from dissension among the various nationalities of which it was composed, so their morale was low. In the month of August, the two armies faced each other on the banks of the Yarmuk, and the Byzantines were routed in a pitched battle lasting several days. After the crushing defeat, in which Theodorus was killed, Heraclius returned to Constantinople in despair, and town after town fell into Muslim hands without resistance, sealing the fate of the whole of Syria in a very short time.
Only Jerusalem, strongly fortified by the Romans, escaped the conquerors wrath; the rest of Palestine went the same way as Syria. The Removal of the Muslim Khalid from his post Soon after the victory at Yarmuk, Caliph Umar removed Khalid [RA] from the supreme command and replaced him by Abu Ubaida ibn al-Jarrah [RAJ, a respected Companion of the Prophet [peace and blessings be upon Him but not as distinguished as Khalid [RA] in the art of warfare. He kept Khalid [RA] as his deputy.
This article was culled from the publications of Deen Communication Limited