Battle of Yarmouk River
The Battle of the Yarmouk (Yarmük, Yarmuk) River was fought between Arab forces of the Rashidun caliphate, led by Abu Ubaidah ibn al-Jarrah and Khalid ibn al-Walid, and Byzantine Empire forces under Mahan of Armenia. The battle took place in Palestine over the course of six days in August 636 next to the Yarmouk River, the largest tributary of the Jordan River. The battle marks the beginning of the first great wave of Islamic military conquests.
In 634 Caliph Abu Bakr ordered Muslim forces to invade Syria, long a Byzantine Empire preserve. The Arab army captured Damascus and took most of Palestine. Faced with these developments, Byzantine emperor Heraclius assembled a large force at Antioch. Organized as five separate armies, it included native Byzantines as well as Slavs, Franks, Armenians, Georgians, and Christian Arabs. Heraclius sought to take advantage of the fact that the Arab forces were separated into four main armies: at Palestine, in Jordan, at Caesarea, and at Emesa (Homs) in Syria. The emperor planned to concentrate his own forces and defeat the Arabs in detail. In June 636 he sent reinforcements under his son Constantine to Caesarea, hoping to tie down Arab forces there, while sending his remaining four armies on converging axes toward Damascus and Emesa.
The Arabs learned the broad outlines of the Byzantine plan from prisoners, and in a council of war Jarrah accepted the advice of his subordinate, Walid, to withdraw from northern and central Syria and concentrate on the plain of Yarmouk, which was more suitable for cavalry operations. Close to the Rashidun stronghold of Najd, this location also offered an escape route.
The Byzantine army camped just north of the Wadi Raqqad. The two sides conducted protracted negotiations, but these soon collapsed. Muslim accounts place the Byzantine force at 200,000–250,000 men and their own army at only 24,000– 40,000 men. Modern estimates are something on the order of 50,000–100,000 for the Byzantines and only 7,500–25,000 for the Arabs. Whatever the numbers, all accounts agree that the Arabs were heavily outnumbered.
Byzantine commander Mahan formed his four armies in a line of battle some 12 miles wide. He distributed the cavalry equally among the armies, situating it in the rear to act as a reserve. He deployed his Arab Christian forces in front. Mounted on camels and horses, they acted as a light screening force and skirmish line.
On the Muslim side, Khalid offered to assume command of the army for the battle; Jarrah, who lacked the experience of his subordinate, accepted. Khalid divided the army into 36 infantry and 4 cavalry units, holding a total front of about 10 miles, with the Muslim left anchored on the Yarmouk River. The cavalry constituted about a quarter of the Muslim strength, and Khalid distributed much of it to his flanks as a reserve to arrest any Byzantine breakthrough there. The remainder he held as a mobile reserve under his personal command in the center. The army thus consisted of 4 subgroups of 9 infantry formations each. Each was organized on the basis of clan or tribe.
The battle opened in mid-August 636, with the two armies less than a mile apart. The Byzantines began with an advance by all four armies in line. The initial assault was not strong, however, as Mahan tried to locate weak points in the Muslim line.
On the second day Mahan attacked at dawn, launching two armies against the Muslim center to fix the Muslim forces in place but with the main thrusts coming on the flanks. The Byzantines made considerable headway in each of their flanking attacks and came close to achieving victory. However, Khalid’s cavalry reserve made the difference; it shored up first the Muslim right and then its left.
On the third day the Byzantines attacked again, this time trying to break through where the Muslim right flank joined the center. Again the Muslim mobile reserve made the difference, averting disaster and pushing the Byzantines back to their original position.
On the fourth day the Byzantines again came close to victory. Believing that the previous day’s assault had severely weakened the Muslim right wing, Mahan resumed the attack there. The Armenian portion of the Byzantine army broke completely through the Muslim line and drove on their camp. Once again Khalid’s cavalry reserve averted disaster. Khalid split it into two main bodies in order to attack the Armenians on each flank. Facing Muslim forces on three sides, the Armenians were forced to withdraw, and the original line was restored. There were significant losses on each side.
Early on the fifth day Mahan dispatched an emissary to the Muslims who asked for a truce of several days to negotiate. Jarrah was willing to accept the proposal, but Khalid was opposed. The battle continued, although there was no major fighting that day.
To this point the Muslims had remained on the defensive. On the sixth day, assuming correctly that Byzantine morale was low, Khalid ordered an attack. He planned to use his cavalry to defeat that of the Byzantines, leaving their infantry without cavalry support and open to attacks from the flanks and rear. He also planned a major simultaneous flanking attack on the Byzantine left that would roll up their line against the river ravine to the west. While Mahan was attempting to organize his cavalry, the Muslim cavalry struck in force, causing the Byzantine horsemen to withdraw to the north and abandon the infantry.
Khalid then directed his cavalry to attack the rear of the Armenian infantry on the Byzantine left. Under the pressure of a three-pronged attack of Muslim cavalry the Armenians broke, carrying the rest of the Byzantine army with them. Pinned against the steep ravines of the Yarmouk so closely that they were hardly able to use their weapons, the Byzantines were slaughtered in large numbers. Many others were killed or maimed by falling into the ravines.The Battle of Yarmouk secured Syria and Palestine for the Muslims. Khalid then recaptured both Damascus and Emesa. Emperor Heraclius returned to Constantinople to consolidate his forces against a Muslim drive in Egypt.
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