In defense of his threatened capital, Sibir, the old Khan rallied once more. He assembled a great army, thirty times that of the Cossacks. For the invaders, however, retreat was more perilous than advance. Yermak went on, and in a great fight on the banks of the Irtish, again prevailed. With his forces reduced by battle and disease to some three hundred effectives, he entered Sibir on October 25, 1581. A few days later the Ostiak tribes, glad to escape their Koran-coercing masters, proffered their allegiance, and the Cossack saddle was on Siberia. But how precarious was their seat! Southward were the myriads of the unconquered hordes of Tatary; only one of the score of their khans had been vanquished. As thistledown is blown before the wind, so could Yermak’s oft-decimated band have been swept away had once the march of the Mongols’ main division turned northward. Girding him round were the self-submitting Ostiaks, loyal for the moment to those who had won them freedom from the old proselyting overlord, but not long to be relied upon once the weight of Cossack tribute--the fur-yassak--began to be felt. But what the Tatar hordes had not, what the Ostiak hunters had not, the three hundred Cossacks had--a man. This man, starting his march as the hunted captain of a band of outlaws, could conquer half a continent. Then over the heads of his employers, the mighty family of Stroganov, over the heads of governors of provinces, of boyars, of ministers to the throne, he could send by his outlaw lieutenant, Ivan Koltso, loftily, imperially, as a prince to a king, his offer of the realm of Siberia to Ivan Vasilevich. Ivan the Terrible, Czar of all the Russias, he who had blinded the architect of St. Basil, lest he plan a second masterpiece; he who had tortured and slain a son, hated less for his intrigues than for his unroyal weakness, responded imperially. Over the long versts Ivan’s courier carried to Yermak a pardon, confirmation as ruler of the newly-won realm and the Czar’s own mantle, an honor accorded only to the greatest, the boyars of Muscovy. Following the messenger eastward there plodded three hundred musket-armed Strelitz to bear aid to the Cossack garrison. Sorely now were these reinforcements needed, for the Ostiak tribes flamed into rebellion against King Stork. With Kutchum’s Tatars, they returned to the attack and besieged Sibir. Once again, though hemmed about by the multitude of his enemies, the valor of Yermak saved his cause. In a totally unexpected sally, in June, 1584, the Tatar camp was surprised, a great number massacred, and the besiegers scattered.