|Location||Judaea, The Byzantine Empire|
|Attacking Army||Rashidun Caliphate (General Khalid ibn al Walid) with about 35,000 men, including 9,000 cavalry.|
|Defending Army||The Byzantine Empire (Emperor Heraclius) with about 60,000 men, including 14,000 cavalry.|
|Result||Major victory for the Islamic Empire.The Muslim Empire continued expanding westward eventually capturing Damascus and Jerusalem, among other major localities.|
|Casualties||Byzantines 5,000-6,000 , Arabs 12,000-17,000|
The Battle of Yarmuk, fought in 636 AD, was the turning point in Arab history that put a stop to any future Muslim attempt to expand into Europe. Fought between Arab general Khalid ibn al Walid and the Byzantine Emperor Heraclius, it showed that Byzantine arms would not be tarnished by the newfound tactics of the Arabs.After the battle, the Arabs were eager to avoid battle with the Byzantines and instead shifted their efforts eastward into central and southern Asia.The Byzantines,on the other hand, learned from Arab Light Cavalry tactics, and utilized them in their later conquest of Central Europe and Russia.
Harnessing the zeal of Arabia's new religion, Caliph Abu Bakr devised a plan of action to expand the tiny Rashidun Caliphate beyond his peoples wildest dreams. A profound mathematician, Abu Bakr had worked out the exact timings involved to knock out his two most immediate enemies in one go. Both Persia and Byzantium were large but essentially weak nations, with a hatred inherited from years of rivalry and warfare. There was no one else of any importance in the area (save the Khazars, who had admittedly slipped through Abu Bakr's calculations) and consequently he felt it would be easiest first to eliminate the Byzantines, the stronger of Arabia's future opponents, and then to use what was left of this force to conquer Persia. Having shared his plans with Khalid ibn al Walid, his strongest commander, he was ready to initiate his invasion plans by the opening months of 636AD.
Brought to battle
The Byzantines, who had been watching their border with Persia at the time, were taken completely by surprise; the last thing they were expecting was invasion from Arabia. However, Emperor Heraclius managed to scrape together an army strong enough to oppose the Arab invasion.His army outnumbered the Arabs, and included heavily armored infantry and cavalry, which would later cut the Arabs' lightly armored, ill-trained soldiers to pieces.
Impressed by the quality of the Byzantine force, Khalid chose to keep back from the enemy, instead concentrating his attention on peppering the Byzantines with arrows from his Arab horsemen. Heraclius, in response, sent forth his finest horse archers, the Vardatorii to skirmish with the Arabs. The two sides took many casualties in this skirmish, after which the Vardatorii retreated. The impetuous Arabs began to pursue, but did so too quickly, leaving their infantry a long way behind the flower of their horsemen. Heraclius had no difficulty in combating the Arabs with his Pronolai cavalry, before sending the cataphracts in to finish the job. In the pursuit that followed, a good three quarters of the Arab horse were destroyed, though the majority of the infantry got away.
Khalid ibn al Walid, an impetuous man, did not take this setback too seriously, within the next year he had invaded Persia and defeated Yazdegird III heavily at the battle of Qadisiya. However, the battle did mark the end of any Western incursions by the Arabs. Though impetuous, Khalid was also cautious - and was most certainly not stupid. He never fought the Byzantines in person again. The Byzantines didn't see their Arab foes in a major battle for another 300 years, until the Byzantine invasion of Muslim Persia.