 Vlad I of Wallachia, a Hungarian vassal, issued an act of submission on 28 May, acknowledging Jadwiga and her husband as Mary's legitimate successors.The widowed king's close supporter, Stibor of Stiboricz, expelled Vlad from Wallachia.Władysław-Jogaila gathered his troops on the Polish-Hungarian border, but , Palatine of Hungary, and , Archbishop of Esztergom, stopped his invasion of Hungary.