565. The Great Northern War: Revenge of the Cossacks (Part 2)

After establishing the city of St Petersburg, what was Peter the Great’s next step in his titanic struggle against Charles XII of Sweden, for mastery of northern and eastern Europe? What drastic, brutal action did he take against Poland, to slow the Swedish advance into his territories? And, after the defection of one of his oldest and most important allies - the leader of the Ukrainian Cossacks - to the Swedes, could Peter and his army survive to fight on?