Andrei of Polotsk Andrei of Polotsk ( , , born ca . 1325 – died on 12 August 1399 in the Battle of the Vorskla River ) was the eldest son of Algirdas , Grand Duke of Lithuania , and his first wife Maria of Vitebsk . He was Duke of Pskov ( through his deputy Yuri , 1342 – 1348 ) and Polotsk ( 1342 – 1387 ) . As the eldest son of the Grand Duke , Andrei claimed his right to the throne after his father ' s death in 1377 . Algirdas left Jogaila , his eldest son with his second wife Uliana of Tver , as the rightful heir . Andrei ' s rivalry with Jogaila , Grand Duke of Lithuania and later King of Poland , eventually led to his demise . Duke of Pskov and Polotsk . In 1342 , Andrei joined his father Algirdas and uncle Kęstutis in a war against the Livonian Order to help the Pskov Republic . The Republic asked him to stay as a duke of Pskov so that his presence would guarantee continuous support from Algirdas . Andrei accepted and was baptized in Orthodox rite ( his pagan name is unknown ) . However , he stayed there for a very short time and returned to Lithuania . Reasons are not entirely clear , but historians speculate it was related to death of his great - uncle Vainius , Duke of Polotsk . Polotsk was vital to Lithuanian interests as it was situated between Lithuania and the Livonian Order . Andrei became the Duke of Polotsk and helped defend Lithuania against Livonian attacks . In Pskov , Andrei left his deputy , otherwise unknown Yuri . Lithuanian historian Alvydas Nikžentaitis speculated that this Yuri could have been a grandson of Gediminas . Yuri remained in Pskov until 1348 when Teutonic Knights organized a large attack against Lithuania ( see Battle of Strėva ) . Pskov ' s army was helping Novgorod against Sweden when Livonian Order attacked Pskovian fortress at Izborsk . Yuri died in the attack . Because Lithuanians were unable to defend Pskov , the city refused to accept another deputy from the Grand Duchy of Lithuania . Andrei responded with repressions : all merchants from Pskov were arrested and their goods confiscated . The friendly relationship between Pskov and Lithuania was terminated . Andrei remained as Duke of Polotsk for the next three decades . Struggle against Jogaila . After death of Algirdas in 1377 , Andrei , as the eldest son , rivaled his half - brother Jogaila , whom Algirdas designated as his heir . Jogaila at the time enjoyed strong support from his uncle Kęstutis . Andrei organized an anti - Lithuanian coalition with Polotsk , Grand Duchy of Moscow , and the Livonian Order . In 1379 , Moscow ' s army attacked eastern territories of the Grand Duchy ; Moscow and Lithuania were at peace since the Treaty of Lyubutsk in 1372 . Andrei ' s brother Dymitr I Starszy did not defend the Principality of Trubetsk and Starodub . However , the Russian army did not remain in taken territories and retreated back to Moscow ; Andrei and Dymitr followed it . Jogaila signed a ten - year truce with the Teutonic Knights on September 29 , 1379 and a truce with the Livonian Order on February 27 , 1380 , thus fracturing the coalition . He further enlisted Mamai , Khan of the Golden Horde , and Oleg II of Ryazan as his allies against Andrei . In 1380 , Andrei and Dymitr fought for Moscow in the Battle of Kulikovo against the Tatars . The Tatars were badly defeated when Jogaila ' s army did not arrive to the battlefield on time . In 1381 , Jogaila attempted to install his loyal brother Skirgaila in Polotsk , the former domain of Andrei . As Skirgaila was laying a siege on the rebellious city , Kęstutis and his son Vytautas took the opportunity to start the Lithuanian Civil War against Jogaila and remove him from the throne . Polotsk voluntarily surrendered to Kęstutis , who reinstated Andrei . Sources do not mention him in 1381 – 1385 . Possibly he was waiting in Polotsk for the feud between Jogaila and Kęstutis to be sorted out . Kęstutis died , but Jogaila and Vytautas reconciled in 1384 . On October 10 , 1385 , Andrei signed a treaty with the Livonian Order in which he surrendered to the Order in exchange for protection against Vytautas and other enemies . According to the treaty , Andrei became Order ' s vassal and received Polotsk as a feudal estate . When Jogaila traveled to Poland to discuss the Union of Krewo , Andrei took the opportunity to renew his war against Lithuania . In 1386 , he attacked territories south east of Polotsk . His cause was helped by the Livonian Order , which attacked Duchy of Lithuania , and by Sviatoslav II of Smolensk , who attacked Mstsislaw , taken from the Principality of Smolensk by Algirdas . However , Sviatoslav suffered a great defeat in the Battle of the Vikhra River and the Principality of Smolensk became a vassal of Lithuania . Capture and release . The Lithuanian army led by Skirgaila attacked Polotsk in 1387 . The Livonian Order did not defend it and the city soon surrendered . Andrei was captured ; his son Simeon died in the fighting and another son Ivan escaped to Pskov , where he was mentioned as a duke in 1389 . Andrei was imprisoned in Poland for seven years . He was released in 1394 by request of Vytautas . After the release Andrei moved to Pskov , where he attempted to negotiate a truce between Pskov and Novgorod . After this event he was mentioned only once – as one of the prominent figures , who perished in the Battle of the Vorskla River in 1399 .