Complex sentence: The royal city of Kraków, occupied since two years by Swedish-Transilvanian garrison of Paul Wirtz and János Bethlen, was besieged by Polish Army of Hetman Jerzy Lubomirski, supported by Holy Roman Empire's troops under Austrian Field Marshal Melchior von Hatzfeldt.
Split into simpler sentences: The royal city of Kraków, had been occupied for two years by a Swedish-Transylvanian garrison led by Paul Wirtz and János Bethlen. It was besieged by Polish Army of Hetman Jerzy Lubomirski, supported by soldiers of the Holy Roman Empireunder Austrian Field Marshal Melchior von Hatzfeldt.