It is unclear why, but Jaunutis, a middle son not mentioned in any written sources before the "coup d'état" accomplished by his brothers, was designated by Gediminas as his heir in Vilnius and consequently became the Grand Duke. His brother Kęstutis, Duke of Trakai, was assisting him in Samogitia. Despite help from Narimantas, Jaunutis was deposed by his brothers Algirdas and Kęstutis in 1345, just four years after Gediminas' death. Jaunutis tried, but failed, to solicit help from his brother-in-law Simeon of Russia and was baptized as "Iwan" in the process. He was forced to reconcile with Algirdas and in compensation received the Duchy of Zasłaŭje, which he ruled until his death in 1366.