Battle of Yarmouk
The Battle of Yarmouk was a major battle between the army of the Byzantine Empire and the Muslim Arab forces of the Rashidun Caliphate. The battle consisted of a series of engagements that lasted for six days in August 636, near the Yarmouk River, along what today are the borders of Syria–Jordan and Syria–Israel, east of the Sea of Galilee. The result of the battle was a complete Muslim victory which ended Byzantine rule in Syria. The Battle of Yarmouk is regarded as one of the most decisive battles in military history, and it marked the first great wave of Islamic conquests after the death of the prophet of Islam Muhammad, heralding the rapid advance of Islam into the then Christian Levant.
In order to check the Arab advance and to recover lost territory, Emperor Heraclius had sent a massive expedition to the Levant in May 636. As the Byzantine army approached, the Arabs tactically withdrew from Syria and regrouped all their forces at the Yarmouk plains close to Arabia where, after being reinforced, they defeated the numerically superior Byzantine army. The battle is considered to be one of Khalid ibn al-Walid's greatest military victories. It cemented his reputation as one of the greatest tacticians and cavalry commanders in history.
During the last Byzantine–Sassanid Wars in 610, Heraclius became the emperor of the Byzantine Empire, after overthrowing Phocas. Meanwhile, the Sassanid Persians conquered Mesopotamia and in 611 they overran Syria and entered Anatolia, occupying Caesarea Mazaca. Heraclius, in 612, managed to expel the Persians from Anatolia, but was decisively defeated in 613 when he launched a major offensive in Syria against the Persians. Over the following decade the Persians were able to conquer Palestine and Egypt. Meanwhile, Heraclius prepared for a counterattack and rebuilt his army. Nine years later in 622, Heraclius finally launched his offensive. After his overwhelming victories over the Persians and their allies in the Caucasus and Armenia, Heraclius, in 627, launched a winter offensive against the Persians in Mesopotamia winning a decisive victory at the Battle of Nineveh thus threatening the Persian capital city of Ctesiphon. Discredited by these series of disasters, Khosrau II was overthrown and killed in a coup led by his son Kavadh II, who at once sued for peace, agreeing to withdraw from all occupied territories of the Byzantine Empire. Heraclius restored the True Cross to Jerusalem with a majestic ceremony in 629.
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