Following Hunyadi's victory over Mehmet II at the siege of Belgrade on 14 July 1456, a period of relative peace began in the region. The sultan retreated to Adrianople, and Branković regained possession of Serbia. Before the end of the year, however, the 79-year-old Branković died. Serbian independence survived him for only another three years, when the Ottoman Empire formally annexed his lands following dissension among his widow and three remaining sons. Lazar, the youngest, poisoned his mother and exiled his brothers, and the land returned to the sultan's subjugation.