On his sea-journey a terrific storm arose that threatened to overwhelm both him and his crew. ‘My Lord,’ exclaimed one of his attendants, ‘I pray you make a vow to God that if He spare you, you also will spare your enemies.’ ‘May God sink this vessel here and now,’ retorted his master, ‘if I spare a single one of them that falls into my hands,’ and the words were an ill omen for his reign, that began once more in 705 when, with the aid of Bulgar troops and of treachery within the capital, Justinian II established himself once more in Constantinople. During six years the Empire suffered his tyranny anew; and those who had previously helped to dethrone him were hunted down, tortured, and put to death. Like Nero of old he burned alive his political enemies, or he would order the nobles of his court who had offended him to be sewn up in sacks and thrown into the sea. At last another rebellion brought a final end to his reign, and that of the house of Heraclius, for both he and his young son were murdered, and the Eastern Empire given up to anarchy. [Sidenote: Leo the Isaurian] The man who did most to save Constantinople from the next Mahometan invasion was one of the military governors of the Empire called Leo the Isaurian. Conscious of his own ability he took advantage of his first successes to seize the imperial crown; and then, having heard that the Mahometan fleet was moored off the shores of Asia Minor, he secretly sent a squadron of his own vessels that set the enemy’s ships on fire. In the panic that ensued more than half the Arabian ships were sunk. About the same time a Mahometan land force was also defeated by the King of the Bulgars, who had allied himself with the Emperor on account of their mutual dread of an Eastern invasion. The result of these combined Christian victories was that the Caliph Moslemah, whose main forces were encamped beneath the walls of Constantinople, grew alarmed lest he should be cut off from support and provisions. He therefore raised the siege, embarked his army in what remained of his fleet, and retreated to his own kingdom, leaving the Christian capital free from acute danger from the East for another three hundred years. Elsewhere the Mahometans pursued their triumphant progress with little check. After the fall of Carthage in 697 North Africa lay almost undefended before them; and the half-savage tribes such as the Berbers, who lived on the borders of the desert, welcomed the new faith with its mission of conversion by the sword and prospects of plunder. It was the Berbers who at the invitation, according to tradition, of a treacherous Spanish Governor, Count Julian, crossed the Strait of Gibraltar and descended on the plains of Andalusia.