The border, in late Chosŏn rhetoric, was an area of pernicious wickedness; living near the border made the people susceptible to corruption and violence. For Chosŏn ministers in the nineteenth century, despite two hundred years of peace, the threat remained. At the same time, the military institutions created to contain it were failing. For much of the late Chosŏn the site of greatest concern was the northern border in P’yŏngan and Hamgyŏng provinces, as this area was the site of the largest rebellion and most foreign incursions in the first half of the nineteenth century. This study takes the northern border as the most fruitful area for an inquiry into the Chosŏn dynasty’s conceptions of and efforts at border defense. Using government rec...