Sejong the Great

Sejong the Great commissioned the development of advanced astronomical instruments, including the armillary sphere and water clock. These tools improved timekeeping and calendar accuracy in Joseon.

Sejong the Great launched military campaigns against the Jurchen tribes in the north, securing the border and establishing the Four Forts and Six Garrisons. This expanded Joseon territory and stabilized the frontier.

King Sejong the Great oversaw the creation of Hangul, the Korean alphabet, to improve literacy among commoners. The script was promulgated in 1446 and remains the writing system of Korea.

Sejong the Great officially promulgated the Hunminjeongeum, the document explaining the new Hangul script. This marked the formal introduction of the alphabet to the Korean people.