Charles was a skilled military leader, and probably considered the invasion to be a risky enterprise; he had resisted the advice of his generals to invade during the Russian winter following the first Battle of Narva (1700). He chose to continue his invasion now because he expected Swedish reinforcements and the alliance of the Cossacks under Ivan Mazepa. The reinforcing Swedish army, however, was ambushed by Russians, and a Russian army under Aleksandr Danilovich Menshikov had destroyed Mazepa's capital and chased him to Charles with just thirteen hundred men.