In the campaign of 624, Chosroes brought up three armies against the emperor. Heraclius defeated them in three great battles. He made so sudden a night attack upon what remained that their general, Sarbar, wakened by the clash of arms, had scarcely time to spring from his bed on horseback, and ride away at full speed, while the conqueror took possession of his golden shield, and even his clothes. In his fourth campaign, that of 625, Heraclius was also victorious. Chosroes avenged the defeat of his troops by falling on the churches of Persia, which he stripped of all their ornaments: and to punish the emperor, he compelled the Christians of his realm to become Nestorians. Fifteen years before, he had, to please his physician, compelled the inhabitants of Edessa to become Eutycheans. Chosroes rallied all his forces for the campaign of 626. He raised three great armies, composed indifferently of freemen and slaves, of natives and foreigners. Sarbar led one of these armies to Chalcedon to besiege Constantinople, on the Asiatic side, while the Khan of the Avars, breaking truce, appeared on the European side, to demand the surrender of the city and all its wealth. Its inhabitants, however, defended themselves with such valour as to repulse both Avars and Persians. The fall of the Avar power begins at this moment. It was henceforth occupied by intestine struggles. Sais led the second army of Chosroes, which was defeated by Theodore, brother of the emperor Heraclius. Heraclius himself broke the third army under the command of Rhazates, at Nineveh, on the 12th December, 627. The battle began in early morning, and ended only in the evening. The Persians lost, besides the commanding general, his three lieutenants, almost all their officers, and nearly the half of their soldiers. The Romans had only fifty killed, but many thousands wounded. These the emperor tended with so much care that only ten died.