In 634 the city of Bostra, capital of the province of Arabia, fell to the Arabs under Omar. Cities on the desert fringe had been raided before. But this was no raid. A great Byzantine army was defeated on the river Yarmuk in Palestine on 20 August 636, which put the whole of Syria at the mercy of the Arabs. Damascus fell at the end of the same year, and by 638 Antioch and Jerusalem were both captured. In 639 Byzantine Mesopotamia fell to the invaders. In 641 began the invasion of Egypt, the granary of the empire, and Alexandria was taken in 646. In the meantime the Arabs had already occupied Cyrenaica and Tripolitania, and were thrusting deep into Asia Minor. By 654 the Arabs possessed a fleet capable of conducting a devastating raid on Rhodes. In spite of some successful resistance by Constans II (641–668) and Constantine IV (668–685), and a peace treaty between Arabs and Byzantines in 659, Arab pressure continued. Annual Arab expeditions into Asia Minor recommenced in 663, and often penetrated as far as Chalcedon, on the Asiatic shore opposite Constantinople. Meanwhile their fleet attacked and occupied Rhodes, Cos and Chios, and established in Cyprus a kind of condominium with the Byzantines, which enabled the island to remain neutral until the tenth century, when it was brought once again under Byzantine control. In 670 Cyzicus, in the Sea of Marmora, was taken, and in 672 Smyrna fell.