Muscovy did not live up to these terms, and the result was a succession of Ukrainian uprisings, directed now against Russia just as they had formerly been aimed at Poland. In the last quarter of the seventeenth century, Russia and Poland made common cause and partitioned Ukraine, making the Dnieper the frontier between their two empires. The most important rebellion against this last measure was that led by Mazeppa in 1709, which was quelled by Peter the Great. After the time of Mazeppa, Russia's policy of repression was pursued openly and ruthlessly. Peter instituted a supervision over the autonomous Ukrainian administration, vesting authority in Muscovite officers, through whose hands passed everything pertaining to the hetman's chancellery. In 1722 the power of the hetmans was cut down to nothing. In 1764 Catherine II. abolished the office altogether. Meanwhile, in order to assure possession of Ukraine, the Russian government was making every effort to assimilate the Ukrainian people. One step toward accomplishing this was the suppression of Ukrainian literature. In 1720 a special censorship over the publication of Ukrainian books was established in Kiev. In 1769 even the printing of Ukrainian primers was forbidden, and Russian text-books were introduced in spite of the protests of Ukrainian educators. Step by step, national feeling was stifled in Ukraine. In 1775, the "Zaporogian Sitch," the last bulwark of Ukraine's autonomy, and the basis of the Ukrainian Army, was destroyed. In 1783 the peasants of Ukraine, free since 1648, when they had thrown off Polish domination, were again subjected by the Russian government to serfdom in its most cruel form. Hundreds of thousands of free peasants and Cossacks, together with millions of acres of Ukrainian land, were distributed among the favorites of Catherine II. This measure had the effect of crushing the resistance to Russification among the Ukrainian nobility, and estranged them from the common people. The serfdom of the small farmer was so profitable for the gentry that the preponderance of the aristocracy became superficially Russian. Under pressure of Russian schooling, administration and military service, they adopted the Russian language and political ideas. To achieve this desirable result, the Muscovite government did not hesitate to persecute ruthlessly anything that could be held as a reminder of the republican regime in Ukraine. At the same time, an analogous Polonization of the upper classes was being carried out in western Ukraine. The last quarter of the century witnessed a temporary eclipse of the Ukrainian spirit of nationalism.