LEO III  . (c . 680-740), surnamed THE ISAURIAN, emperor of the East, 717-740 . Born about 68o in the Syrian province of Commagene, he rose to distinction in the military service, and under Anastasius II. was invested with the command of the eastern army . In 717 he revolted against the usurper Theodosius III. and, marching upon Constantinople, was elected emperor in his stead . The first year of Leo's reign saw a memorable siege of his capital by the Saracens, who had taken advantage of the civil discord in the Roman empire to bring up a force of 80,000 men to the Bosporus . By his stubborn defence the new ruler wore out the invaders who, after a twelve months' investment, withdrew their forces . An important factor in the victory of the Romans was their use of Greek fire . Having thus preserved the empire from extinction, Leo proceeded to consolidate its adminis-tration, which in the previous years of anarchy had become completely disorganized . He secured its frontiers by inviting Slavonic settlers into the depopulated districts and by restoring the army to efficiency; when the Arabs renewed their invasions in 726 and 739 they were decisively beaten . His civil reforms include the abolition of the system of prepaying taxes which had weighed heavily upon the wealthier proprietors, the elevation of the serfs into a class of free tenants, the remodelling of family and of maritime law . These measures, which were embodied in a new code published in 740, met with some opposition on the part of the nobles and higher clergy .

But Leo's most striking legislative reforms dealt with religious matters . After an apparently successful

attempt to enforce the baptism of all Jews and Montanists in his realm (722), he issued a series of edicts against the worship of images (726-729) . This prohibition of a custom which had undoubtedly given rise to grave abuses seems to have been inspired by a genuine desire to improve public morality, and received the support of the official aristocracy and a section of the clergy . But a majority of the theologians and all the monks opposed these measures with uncompromising hostility, and in the western parts of the empire the people refused to obey the edict . A revolt which broke out in Greece, mainly on religious grounds, was crushed by the imperial fleet (727), and two years later, by deposing the patriarch of Constantinople, Leo suppressed the overt opposition of the capital . In Italy the defiant attitude of Popes Gregory II. and III. on behalf of image-worship led to a fierce quarrel with the emperor . The former summoned councils in Rome to anathematize and excommunicate the image-breakers (730, 732); Leo retaliated by transferring southern Italy and Greece from the papal diocese to that of the patriarch . The struggle was accompanied by an armed outbreak in the exarchate of Ravenna (727), which Leo finally endeavoured to subdue by means of a large fleet . But the destruction of the armament by a storm decided the issue against him; his south Italian subjects successfully defied his religious edicts, and the province of Ravenna became detached from the empire . In spite of this partial failure Leo must be reckoned as one of the greatest of the later Roman emperors . By his re-solute stand against the Saracens he delivered all eastern Europe from a great danger, and by his thorough-going reforms he not only saved the empire from collapse, but invested it with a stability which enabled it to survive all further shocks for a space of five centuries . See E .

Gibbon, The Decline and Fall of the Roman Empire (ed . Bury, 1896), v . 185 seq., 251 seq. and appendices, vi . 6-I2, J . B . Bury, The Later Roman Empire (1889), ii . 401-449; K . Se enk, Kaiser Leo III . (Halle, 1880), and in Byzantinische Zeitschrift (1896), v . 257-301; T . Hodgkin, Italy and her Invaders (1892, &e.), bk. vii., chs . 11, 12 .

See also

ICONOCLASTS .