In the meanwhile the Northern War had broken out, and this radically changed the situation. Charles XII, a man of superb military talent and a ruthless desire to employ it, had inherited the Swedish army at a time when Sweden, as a result of the Thirty Years War, was one of the great powers of Europe. In 1700 he attacked Russia and badly defeated Peter at the battle of Narva. Then he wasted the next years in trying to depose August II, King of Poland, and replace him with Stanislas Leszczynski, a move in which he had the support of all the anti-Russian factions of Poland. This alliance of the King of Sweden and one faction of the Poles against the Tsar of Russia and the King of Poland opened new vistas to the Kozaks, who had not forgotten the negotiations between Khmelnitsky and the Swedes during the great Kozak revolt of a half century earlier. Intermittent hostilities between the forces of King August and the Kozaks of Paly, the leader of the Kozaks in Poland, led Paly to appeal for aid to Mazepa, but at the moment Peter was interested in maintaining relations with the King and he forbade Mazepa to interfere. Instead of that he offered himself to help in the suppression of Paly. This of course displeased Mazepa for he had hopes of bringing Western Ukraine under his control, but again he was compelled to wait. Finally in 1704 Peter ordered Mazepa to enter Western Ukraine to subdue the Polish nobles friendly to Charles. Mazepa obeyed in his own special way to aid the Kozaks. However, he distrusted the influence of Paly, who represented more democratic traditions, arrested him and reported to Peter what was probably the truth: that Paly was in touch with the Swedes. He replaced him with one of his own relatives, a Colonel Omelchenko, and finally this man was accepted by the Kozaks of the west and still more warmly by the population of the various towns. However, in 1707 Peter ordered him to restore Western Ukraine to Polish rule. This Mazepa was unwilling to do, although instead of open disobedience to the Tsar’s order, he made all kinds of excuses and promises, and evaded action. Mazepa had apparently already made up his mind to strike for the independence of Ukraine, if Charles showed any sign of success. The war was dragging on and Charles, true to his character, was dashing hither and yon through Europe, wasting his troops, winning victory after victory but not concentrating on any definite policy. The Kozak hetman therefore opened some sort of negotiations with Stanislas Leszczynski, and through him he could of course reach Charles. Yet he was so overcautious that he kept even his closest friends from knowing of his plans and continued to strengthen his bonds with Peter.