The first step of Russian invasion in this quarter was made in 1602. In that year a Russian force captured the city of Khiva, but was not able to hold its prize. In 1703, during the reign of Peter the Great, the Khan of Khiva placed his dominions under Russian rule, and during the century Khiva continued friendly, but after the opening of the nineteenth century it became bitterly hostile. Meanwhile Russia was making its way towards the Caspian and Aral seas. In 1835 a fort was built on the eastern shore of the Caspian and several armed steamers were placed on its waters. Four years later war broke out with Khiva, and the khan was forced to give up some Russian prisoners he had seized. In 1847 a fort was built on the Sea of Aral, at the mouth of the Syr-Daria, whose waters formed the only safe avenue to the desert-girdled khanate of Khokand. Steamers were brought in sections from Sweden, being carried with great labor across the desert to the inland sea, on whose banks they were put together and launched. Armed with cannon, they quickly made their appearance on the navigable waters of the Syr. The Amu-Daria is not navigable, so that the Syr at that time formed the only ready channel of approach to Khokand, and from this to the other khanates, none of which could be otherwise reached without a long and dangerous desert march. Russia thus, by planting herself at the mouth of the Syr, had gained the most available position from which to begin a career of conquest in Central Asia. War necessarily followed these steps of invasion. In 1853 the Russians besieged and captured the fort of Ak Mechet, on the Syr, thought by its holders to be impregnable. Up the river, bordered on each side by a narrow band of vegetation from which a desert spread away, the Russians gradually advanced, finally planting a military post within thirty-two miles of Tashkend, the military key of Central Asia. Such was the state of affairs in 1862, when war arose between the khanates themselves, and the Emir of Bokhara invaded and conquered Khokand. Russia looked on, awaiting its opportunity. It came at length in an appeal from the merchants of Tashkend for protection. The protection came in true Russian style, a Cossack force marching into and occupying the town, which has since then remained in Russian hands. The movement of invasion went on until a large portion of Khokand was seized. This audacious procedure of the Muscovites, as the Emir of Bokhara regarded it, roused that ruler to a high pitch of fury and fanaticism. He imprisoned Colonel Struve, an eminent Russian astronomer who was on a mission to his capital, and declared a holy war against the invading infidels.