During the summer Jogaila met Vytautas in person in the Ostrovo (Polish: "Ostrów", Lithuanian: "Astravas") mansion near Lida in modern Belarus. Its exact location is not known, but one suggested site is near Dzitva River to the east of the village of Yantsavichy. Jogaila handed over the government of Lithuania to his cousin in exchange for peace. Vytautas was to rule Lithuania as its Grand Duke ("Magnus Dux"), while Jogaila adopted the higher title Supreme Prince ("Prince Supremus"). Thus Vytautas recognized that he was Jogaila's vassal whose lands upon his death would pass to the King of Poland. Skirgaila was removed from the Duchy of Trakai to become Duke of Kiev. The treaty was ratified in separate documents of the Polish and Lithuanian states as well as in separate documents signed by Anna, wife of Vytautas, and Jadwiga, wife of Jogaila. The treaty was enacted in several phases, adjusting the equivocal points stated in the Union of Krewo. The treaty strengthened Lithuania's central government as well.