Complex sentence: On March 30,1599 Sigismund of Transylvania abdicated the throne in favor of his cousin, Andrew Báthory (1599), who was loyal to the Poles and promptly demanded that Michael the Brave accept his suzerainty.
Split into simpler sentences: On March 30,1599 Sigismund Báthory abdicated the throne in favor of his cousin, Andrew Báthory (1599). The new prince was loyal to the Poles and promptly demanded that Michael the Brave accept his suzerainty.