Gapsan

Gapsan developed as a fortified district in Korea's northeastern mountains. In 1391 the late Goryeo government incorporated the territory as Gapju and established a military command. Early Joseon rulers sought to bring its substantial Jurchen population under royal authority. The district received the name Gapsan in 1413; two years later a county magistrate replaced the military commander, combining civil administration with frontier defence.

Distance from Gilju helped make Gapsan an independent garrison in 1455. In 1461 Han Myeonghoe argued that its exposed position and weak forces required an experienced, higher-ranking official. Gapsan consequently became a protectorate, whose magistrate also commanded its troops, with a subordinate commander at Unchong Fort. Later military reorganizations altered the garrison's responsibilities, but local government and military command remained closely joined.