When did the cousin of the Grand Duke of Lithuania die?
Vytautas Vytautas (c. 1350 – October 27, 1430), also known as Vytautas the Great (Lithuanian: "   ", Belarusian: "Вітаўт Кейстутавіч (Vitaŭt Kiejstutavič)" , Polish: "Witold Kiejstutowicz" , Rusyn: "Vitovt", Latin: "Alexander Vitoldus") from the 15th century onwards, was a ruler of the Grand Duchy of Lithuania, which chiefly encompassed the Lithuanians and Ruthenians. He was also the Prince of Hrodna (1370–1382), Prince of Lutsk (1387~1389), and the postulated king of the Hussites.
David of Hrodna David (Belarusian: Давыд Гарадзенскі , Lithuanian: "Dovydas Gardiniškis" , killed in 1326) was a castellan of Hrodna and one of the most famous military commanders of Gediminas, Grand Duke of Lithuania. He might have been the son of Daumantas of Pskov and great grandson of Alexander Nevsky. Maciej Stryjkowski claims that David was married to one of the daughters of Gediminas. He seems to have been a middleman between the pagan Gediminas and the Christian princes of the Rurikid family and frequently led in battle the united Lithuanian-Ruthenian armies.