Career
In 1386 a war broke out between Algirdas" sons, Skirgaila and Andrei of Polotsk. The latter fled from Polotsk to Smolensk and asked Yury"s father for help. The armies of Smolensk and Skirgaila clashed near Mstislavl in the Battle of the Vikhra River.
In 1395, while Yury was visiting his father-in-law, Oleg Korotopol of Ryazan, Grand Duke Vytautas the Great (Vitovt) of Lithuania took Smolensk and installed his governor there.
Four years later, Vytautas was routed by the Tatars in the Battle of the Vorskla River. In 1401, Yury and Oleg made use of his plight to retake Smolensk and Bryansk, where the pro-Lithuanian boyars were promptly executed.
In fall 1401, Vytautas laid siege to Smolensk but was forced to retreat after signing an armistice. Two years later, Smolensk withstood a two-week siege by Vytautas.
Solicitous to preclude a new attack, Yury went to the Grand Duchy of Moscow to ask Vasily I for help against Vytautas (who was Vasily"s father-in-law).
Thus Smolensk was lost to Russians for more than a century. In 1406, he returned to Moscow, reconciled himself with Vasily and was sent to govern Torzhok in his name.