When did the cousin of the Grand Duke of Lithuania die?
Lithuanian Civil War (1389–92) The Lithuanian Civil War of 1389–92 was the second civil conflict between Jogaila, King of Poland and Grand Duke of Lithuania, and his cousin Vytautas. At issue was control of the Grand Duchy of Lithuania, then the largest state in Europe. Jogaila had been crowned King of Poland in 1386; he installed his brother Skirgaila as ruler of Lithuania. Skirgaila proved unpopular and Vytautas attempted to depose him. When his first attempt to take the capital city of Vilnius failed, Vytautas forged an alliance with the Teutonic Knights, their common enemy – just as both cousins had done during the Lithuanian Civil War between 1381 and 1384. Vytautas and the Knights unsuccessfully besieged Vilnius in 1390. Over the next two years it became clear that neither side could achieve a quick victory, and Jogaila proposed a compromise: Vytautas would become Grand Duke and Jogaila would remain Superior Duke. This proposal was formalized in the Ostrów Agreement of 1392, and Vytautas turned against the Knights. He went on to reign as Grand Duke of Lithuania for 38 years, and the cousins remained at peace.
Albert Frederick, Duke of Prussia Albert Frederick (German: "Albrecht Friedrich" , Polish: "Albrecht Fryderyk" ; 7 May 1553, in Königsberg – 28 August 1618, in Fischhausen, Rybaki) was Duke of Prussia from 1568 until his death. He was a son of Albert of Prussia and Anna Marie of Brunswick-Lüneburg. He was the second and last Prussian duke of the Ansbach branch of the Hohenzollern family.