Indonesia's Youth Pledge Day

From the Indonesian town of Purworejo in the province of Central Java. The stamps from 2023 commemorate the 95th anniversary of Youth Pledge Day. It's a nationalist celebration that was started in 1928 at a youth conference when a declaration of national unity was made: one motherland, one nation, and one language. It was part of a larger push for independence from Dutch rule, which was achieved at the end of the Indonesian National Revolution in 1949.