The Cossacks were a huge community of runaway serfs, free men and adventurers living on the frontier lands of the steppe, from the Ukraine eastwards to the River Don. They were proud of their independence, their Orthodox faith, and of the military help they could bring to the rulers of Muscovy - if they chose. But in the Ukraine, they also fell under the control of the Catholic Poles, and the story of their struggle with the Poles - and their hatred of the Jews who served them - in the seventeenth century is the main action of the 'Cossack' chapter of RUSSKA. (See also Karpenko). The subsequent revolt of the Cossack 'hetman' Mazeppa against Peter the Great occurs in 'Peter'.