Trakai Island Castle lost its military importance soon after the Battle of Grunwald, when the chief enemy of the Grand Duchy of Lithuania was defeated by the Polish-Lithuanian army. The castle was transformed into a residence and newly decorated from the inside. New frescos were painted on its walls, which have been partially preserved.
After the Battle of Grunwald, Trakai Island Castle lost its military importance as the main enemy of the Grand Duchy of Lithuania was defeated by the Polish-Lithuanian army. The castle was then transformed into a residence and decorated anew with new frescoes on its walls that have been partially preserved.