He had reckoned without a force which had again and again won the battle for Russia,[541] and committed the fatal mistake of starting from his base at Orenburg in November, a month which brought his army to the centre of the Ust Urt at the most inclement season of the year. The sufferings of men and beasts in the ice-storms which swept over the desert in the winter of 1839 are paralleled only by those endured by Napoleon’s legions during the retreat from Moscow. The expedition struggled on as far as Ak Bulak, about half-way to the Khivan frontier, and was there fain to retreat, leaving the bones of 1000 men and 8000 camels whitening the pitiless sands. Nothing daunted by his failure, Perofski set about the organisation of a second attempt on a far more elaborate scale, but it was rendered unnecessary by the submission of the Khivans. The ruler, `Alā Kulī Khān, was cowed by the persistence and the might of Russia, and in 1840 he despatched an embassy to Orenburg, accompanied by more than 400 released Slavs. Perofski accepted the olive-branch, and in 1842 a treaty of peace and alliance was concluded with the new ruler. The failure of the expedition of 1840 had shown the incurable defects of Orenburg as a base for operations in Central Asia. If the trackless steppes, the oases teeming with robber-tribes, were to be dominated by Russian influence, some route must be chosen which possessed the advantage of water transport. The vast lake known as the Sea of Aral is connected with the heart of Asia by the Sir and the Amū Daryā, and is easier far to traverse than the steppes on either side. Batakoff explored it thoroughly in 1844, employing vessels brought in sections from Orenburg. Four years later a fort named Kazalinsk was erected at the mouth of the Sir Daryā, and, ere many months had elapsed, Russia was in possession of a chain of strongholds completely commanding the lower reaches of the great river. These precautionary measures raised an intense irritation in the breast of the Khān of Kokand, who claimed the whole course of the Sir Daryā as his own. His subjects were encouraged to invade Russian territory, compelling costly reprisals. In order to put a period to these aggressions, Perofski attacked the fortress of Ak Mechet, 280 miles from the embouchure of the Sir Daryā, and after an abortive attempt took it by storm in 1853. Thus the second great highway of Central Asia fell under Russian control, and it was soon afterwards navigated by a steamer constructed in Sweden, and brought in sections with incredible labour by way of Nijni Novogorod. The amazement excited in the nomads by the spectacle soon died away, and Perofski was besieged by the Kokandis in vain. The grip of Russia tightened. In 1854 an expedition penetrated the valley of the Ili, and a fort was built at Verni, between the lakes of Balkash and Issik Kul. But between this stronghold and Perofski there was a gap of more than 500 miles, which included the