Complex sentence: He and supporters Prince Fedor Ivanovich Belsky and Ivan Yu Golshansky decided to overthrow the Grand Duke of Lithuania Casimir IV and to build on the Lithuanian throne Mikhail, as a descendant of Grand Duke Algirdas.
Split into simpler sentences: He and supporters Prince Fedor Ivanovich Belsky and Ivan Yu. Holshansky decided to overthrow the Grand Duke of Lithuania Casimir IV and to build on the Lithuanian throne Mikhail, as a descendant of Grand Duke Algirdas.