After the death of Justinian, whose power held at bay the Vandals and the Goths, the Persians, and the Turks of the Volga, and after the peaceful times of his nephew, Justin II., and of Tiberius II., who married the widow of Justin, Maurice the Cappadocian--of Roman origin--was emperor for twenty years, till he was murdered in 602 A. D. by the centurion Phocas, elected emperor by the discontented army, and attacked by Khosrau II., the Sassanian ruler of Persia. The Byzantine empire had fallen on evil days, and Heraclius, the exarch of Africa, refused tribute to Phocas. Khosrau I. had conceived the ambitious idea of conquering Western Asia; but he was held in check by Justinian, who was allied to the Turks on his north and to the Sabean kings on the south. The grandson (Khosrau II.) took advantage of the weakness of Phocas, and attacked Aleppo and Antioch in 610 A. D., while Heraclius, son of the exarch, was besieging the upstart centurion in Byzantium. For ten years Khosrau II. held Chalcedon, and the Persian forces faced the new Greek emperor at Constantinople. The victorious Sassanian entered Alexandria, and in 614 A. D. the Persians besieged Jerusalem. Muhammad at Mekkah watched the war, and predicted that in spite of the defeat of the Greeks they would triumph a few years later.[440] Meanwhile, the Holy City fell to the Persians in June[441]; and, according to a contemporary account in the Paschal Chronicle, a terrible massacre of monks and nuns followed. The churches were laid in ruins; the Holy Sepulchre basilica, built by Constantine, was burned down; the Patriarch Zacharias and the True Cross were taken away to Persia as hostages. Mediæval writers state that the corpses of the martyrs were buried at the “Charnel House [or, Cave] of the Lion,” beside the Mâmilla Pool outside Jerusalem, on the west,[442] where a subterranean chapel still exists. The prediction of Muḥammad was speedily fulfilled. Heraclius drove the Persians out of Asia Minor in 622 A. D.--the year of the Hejirah--and struck boldly at the heart of their empire. He advanced nearly to Ispahan, and in five years he so ruined Sassanian power as to leave Persia a prey to the Moslems ten years later. His advance forced Khosrau II. to retreat from Palestine, and early in 628 the latter was murdered by his son Siroes, who made an ignominious peace with the Byzantines. Thus, in the following year, Heraclius made a triumphal entry by the Golden Gate into Jerusalem, at the Feast of the Exaltation of the Cross on September 14, and bore the sacred relic on his shoulder, while the patriarch, having died in captivity, was succeeded by Modestus, his vicar. [Sidenote: MODESTUS]