HERACLIUS ('HpaeXaos) (c. 575-642)  , East Roman emperor, was born in Cappadocia . His father held high military command under the emperor Maurice, and as governor of Africa maintained his independence against the usurper Phocas (q.v.) . When invited to head a rebellion against the latter, he sent his son with a fleet which reached Constantinople unopposed, and precipitated the dethronement of Phocas . Proclaimed emperor, Heraclius set himself to reorganize the utterly disordered administration . At first he found himself helpless before the Persian armies (see PERSIA: Ancient History; and CHOSaoES II.) of Chosroes II., which conquered Syria and Egypt and since 616 had encamped opposite Constantinople; in 618 he even proposed in despair to abandon his capital and seek a refuge in Carthage, but at the entreaty of the patriarch he took courage . By securing a loan from the Church and suspending the corn-distribution at Constantinople, he raised sufficient funds for war, and after making a treaty with the Avars, who had nearly surprised the capital during an incursion in 619, he was at last able to take the field against Persia . During his first expedition (622) he failed to secure a footing in Armenia, whence he had hoped to take the Persians in flank, but by his unwearied energy he restored the discipline and efficiency of the army . In his second campaign (624-26) he penetrated into Armenia and Albania, and beat the enemy in the open field . After a short stay at Constantinople,which his son Constantine had successfully defended against renewed incursions by the Avars, Heraclius resumed his attacks upon the Persians (627) . Though deserted by the Khazars, with whom he had made an alliance upon entering into Pontus,; he gained a decisive advantage by a brilliant march across the Armenian highlands into the Tigris plain, and a hard-fought victory over Chosroes' general, Shahrbaraz, in which Heraclius distinguished himself by his personal bravery . A subsequent revolution at the Persian court led to the dethronement of Chosroes in favour of his son Kavadh II . (q.v.); the new king promptly made peace with the emperor, whose troops were already advancing upon the Persian capital Ctesiphon (628) .

Having thus secured his eastern frontier, Heraclius returned to Constantinople with ample spoils, including the true

cross, which in 629 he brought back in person to Jerusalem . On the northern frontier of the empire he kept the Avars in check by inducing the Serbs to migrate from the Carpathians to the Balkan lands so as to divert the attention of the Avars . The triumphs which Heraclius had won through his own energy and skill did not bring him lasting popularity . In his civil administration he followed out his own ideas without deferring to the nobles or the Church, and the opposition which he encountered from these quarters went far to paralyse his attempts at reform . Worn out by continuous fighting and weakened by dropsy, Heraclius failed to show sufficient energy against the new peril that menaced his eastern provinces towards the end of his reign . In 629 the Saracens made their first incursion into Syria (see CALIPHATE, section A, § 1); in 636 they won a notable victory on the Yermuk (Hieromax), and in the following years conquered all Syria, Palestine and Egypt . Heraclius made no attempt to retrieve the misfortunes of his generals, but evacuated his possessions in sullen despair . The remaining years of his life he devoted to theological speculation and ecclesiastical reforms . His religious enthusiasm led him to oppress his Jewish subjects; on the other hand he sought to reconcile the Christian sects, and to this effect propounded in his Ecthesis a conciliatory doctrine of monothelism . Heraclius died of his disease in 642 . He had been twice married; his second union, with his niece Martina, was frequently made a matter of reproach to him . In spite of his partial failures, Heraclius must be regarded as one of the greatest of Byzantine emperors, and his early campaigns were the means of saving the realm from almost certain destruction .