Instead of pressing on to Novgorod, for some unknown reason Bati turned south, and, marching two hundred miles, laid siege to the strong fortress of Kozelsk, in the principality of Kalouga. The garrison, warned of the advance of the foe, made the most heroic resistance. For four weeks they held their assailants at bay, banking every effort of the vast numbers who encompassed them. A more determined and heroic defense was never made. At last the fortress fell, and not one soul escaped the exterminating sword. Bati, now satiated with carnage, retired, with his army, to the banks of the Don. Yaroslaf, prince of Kief, and brother of Georges II., hoping that the dreadful storm had passed away, hastened to the smouldering ruins of Vladimir to take the title and the shadowy authority of Grand Prince. Never before were more conspicuously seen the energies of a noble soul. At first it seemed that his reign could be extended only over gory corpses and smouldering ruins. Undismayed by the magnitude of the disaster, he consecrated all the activity of his genius and the loftiness of his spirit to the regeneration of the desolated land. In the spacious valleys of the Don and its tributaries lived the powerful nation of the Polovtsi, who had often bid defiance to the whole strength of Russia. Kothian, their prince, for a short time made vigorous opposition to the march of the conquerors. But, overwhelmed by numbers, he was at length compelled to retreat, and, with his army of forty thousand men, to seek a refuge in Hungary. The country of the Polovtsi was then abandoned to the Tartars. Having ravaged the central valleys of the Don and the Volga, these demoniac warriors turned their steps again into southern Russia. The inhabitants, frantic with terror, fled from their line of march as lambs fly from wolves. The blasts of their trumpets and the clatter of their horses' hoofs were speedily resounding in the valley of the Dnieper. Soon from the steeples of Kief the banners of the terrible army were seen approaching from the east. They crossed the Dnieper and surrounded the imperial city, which, for some time anticipating the storm, had been making preparation for the most desperate resistance. The ancient annalists say that the noise of their innumerable chariots, the lowing of camels and of the vast herds of cattle which accompanied their march, the neighing of horses and the ferocious cries of the barbarians, created such a clamor that no ordinary voice could be heard in the heart of the city.