On September 8, Lithuania celebrates the Day of the coronation of Vytautas the Great and thanksgiving for the defense of the independence and freedom of the Grand Duchy of Lithuania from the Commonwealth.
Vytautas the Great (Great Prince of the Grand Duchy of Lithuania, 1350-1430), since 1392 the Grand Duke of Lithuania, son of Keistut. After the union of Lithuania with Poland in 1385, Vytautas (Vitovt), relying on the Lithuanian and Russian boyars who lived in the Russian regions of Lithuania, fought for the independence of Lithuania from Poland.
On August 4, 1392, in Ostrov (on the border of Lithuania and Poland), Vytautas and the Polish king Jagiello signed an agreement under which Vytautas was transferred to the Principality of Trakai, and he became the de facto ruler of the Grand Duchy of Lithuania. In a short time, Vytautas strengthened the centralized power and eliminated the consequences of internal strife.