Battle of Yarmouk - Prelude

Prelude

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.

Meanwhile there had been rapid political development in Arabia, where Prophet Mohammad had been preaching Islam and by 630, he had successfully united most of the Arabia under a single political authority. When the Prophet died in June 632, Abu Bakr was elected Caliph and his political successor. Troubles emerged soon after Abu Bakr's succession, when several Arab tribes openly revolted against Abu Bakr, who declared war against the rebels. In what became known as the Ridda wars (Arabic for the Wars of Apostasy, 632–33), Abu Bakr managed to unite Arabia under the central authority of the Caliph at Medina.

Once the rebels had been subdued, Abu Bakr began a war of conquest, beginning with Iraq. Sending his most brilliant general, Khalid ibn al-Walid, Iraq was conquered in a series of successful campaigns against the Sassanid Persians. Abu Bakr's confidence grew, and once Khalid established his stronghold in Iraq, Abu Bakr issued a call to arms for the invasion of Syria in February 634. The Muslim invasion of Syria was a series of carefully planned and well coordinated military operations that employed strategy instead of pure strength to deal with Byzantine defensive measures. The Muslim armies, however soon proved to be too small to handle the Byzantine response, and their commanders called for reinforcements. Khalid was sent by Abu Bakr from Iraq to Syria with reinforcements and to lead the invasion. In July 634, the Byzantines were decisively defeated at Ajnadayn. Damascus fell in September 634, followed by the Battle of Fahl where the last significant garrison of Palestine was defeated and routed.

Caliph Abu Bakr died in 634. His successor, Umar, was determined to continue the Caliphate Empire's expansion deeper into Syria. Though previous campaigns led by Khalid were successful, he was replaced by Abu Ubaidah. Having secured southern Palestine, Muslim forces now advanced up the trade route where Tiberias and Baalbek fell without much struggle and the Muslims conquered Emesa early in 636. From thereon, the Muslims continued their conquest across the Levant.