As the city commanding the southern entrance of the celebrated pass across the Taurus known as the Cilician Gates, Tarsus served as a base for major military campaigns against the territory of the Greeks. In Muawiyah's time and later a major campaign was undertaken every summer and a minor one every winter as a matter of routine. The objective, as in the case of the traditional bedouin raids, was booty, though the dim spectacle of Byzantium may have beckoned from the distance. At no time did Arabs establish a firm foothold in Asia Minor. Their main military energy followed the line of least resistance and was directed eastward and westward. The Taurus and Anti-Taurus blocked their northward expansion permanently. No part of Asia Minor ever became Arabic-speaking, and its basic population was never Semitic.
The recurring raids into Asia Minor did at last reach the capital, in 668, only thirty-six years after Muhammad's death. The army wintered at Chalcedon (the Asiatic suburb of Constantinople), where it suffered severely from want of provisions and from disease'. Muawiyah sent his pleasure-loving son Yazid with reinforcements early in 669, and the capital was besieged, doubtless with naval support. The siege was raised that summer, and the army withdrew with its booty. Again in 674 the Arabs reached the Straits, occupying the peninsula of Cyzicus, which projects from Asia Minor into the Sea of Marmara. For six years this spot served as a naval base for a Moslem fleet, as winter headquarters for the invading army and as a base for spring and summer attacks. The city was reportedly saved by the use of Greek fire, a newly invented highly combustible com- pound which would burn even on or under water. The inventor was a Syrian refugee from Damascus named Cal- linicus. This was perhaps the first time this 'secret weapon 5 was used. The Byzantines kept its formula unrevealed for several centuries, after which the Arabs acquired it; but it has since been lost. Greek accounts dilate on the disastrous
