consolidate his control over Armenia and most importantly, initiate a major army reform with lasting effect: the establishment of the themata, the large territorial commands into which Anatolia, the major contiguous territory remaining to the Empire, was divided. The remains of the old field armies were settled in each of them, and soldiers were allocated land there in payment of their service. The themata would form the backbone of the Byzantine defensive system for centuries to come. Attacks against Byzantine holdings in Africa, Sicily and the East After his victory in the civil war, Muawiyah launched a series of attacks against Byzantine holdings in Africa, Sicily and the East. By 670, the Muslim fleet had penetrated into the Sea of Marmara and stayed at Cyzicus during the winter. Four years later, a massive Muslim fleet reappeared in the Marmara and re-established a base at Cyzicus, from there they raided the Byzantine coasts almost at will. Finally in 676, Muawiyah sent an army to invest Constantinople from land as well, beginning the First Arab Siege of the city. Constantine IV (r. 661–685) however used a devastating new weapon that came to be known as "Greek fire", invented by a Christian refugee from Syria named Kallinikos of Heliopolis, to decisively defeat the attacking Umayyad navy in the Sea of Marmara, resulting in the lifting of the siege in 678. The returning Muslim fleet suffered further losses due to storms, while the army lost many men to the thematic armies who attacked them on their route back. Among those killed in the siege was Eyup, the standard bearer of Muhammed and the last of his companions; to Muslims today, his tomb is considered one of the holiest sites in Istanbul. The Byzantine victory over the invading Umayyads halted the Islamic expansion into Europe for almost thirty years. The setback at Constantinople was followed by further reverses across the vast Muslim empire. As Gibbon writes, "this Mahometan Alexander, who sighed for new worlds, was unable to preserve his recent conquests. By the universal defection of the Greeks and Africans he was recalled from the shores of the Atlantic." His forces were directed at putting down rebellions, and in one such battle he was surrounded by insurgents and killed. Then, the third governor of Africa, Zuheir, was overthrown by a powerful army, sent from Constantinople by Constantine IV for the relief of Carthage. Meanwhile, a