In the mid-17th century, a Cossack military quasi-state, the Zaporozhian Host, was formed by Dnieper Cossacks and by Ruthenian peasants who had fled Polish serfdom. Poland exercised little real control over this population, but found the Cossacks to be a useful opposing force to the Turks and Tatars, and at times the two were allies in military campaigns. However, the continued harsh enserfment of peasantry by Polish nobility and especially the suppression of the Orthodox Church alienated the Cossacks.