the later King Władysław II Jagiełło of Poland (born Jogaila, son of Algirdas, a brother of Kęstutis). The union produced at least four children: Daughter (Olga?) (1373/76 - c. 8 December 1401), who married firstly in 1388 to Voivode Petru I of Moldavia and secondly with the Moldavian magnate Wilczę. Janusz (1376/81 - c. 18 October 1422). Bolesław (1385/86 - c. 4 May 1424). Konrad (c. 1400 - 9 December 1412/13). Janusz I survived all his children and passed, by testament, his domains to his eldest surviving grandson, Bolesław IV (son of the second son, Bolesław). He died on 8 December 1429 at Czersk, and was buried at St. John's Archcathedral, Warsaw. References 1429 deaths Dukes of Masovia People in the Battle of Grunwald Year of birth uncertain