Mazepa

The work by the Russian historian of the Ukrainian origin Nikolay Ivanovich Kostomarov (1817 - 1885) touches upon the personality and deeds of the odious person of the XVIII century - the hetman Ivan Mazepa`s story. What did make the close to Peter I person betray the tsar - patriotic or just private interests? Which consequence did Mazepa`s turn to the Swedish king`s side Karl XII have to Russia?