Complex sentence: Offended and angered by Sigismund, the boyars dragged their feet on supporting Władysław--they were divided between electing Vasily Galitzine, Michael Romanov (also 15 years old), or the second False Dmitriy.
Split into simpler sentences: Offended and angered by Sigismund, the boyars dragged their feet on supporting Władysław. They were divided between electing Vasily Galitzine, Michael Romanov (also 15 years old), or the second False Dmitriy.