This article explains why the Chosŏn government and the military in particular expanded state control over forests in the seventeenth century and analyzes the implications of forest administration in a preindustrial polity. From 1592 to 1598, the Chosŏn dynasty suffered invasions from Japan that displaced much of the Korean population and devastated the economy and environment. The crucial role of the navy during the war, along with a dire postwar situation, heightened government anxieties about deforestation and timber scarcity. Thus, in the seventeenth century, the Chosŏn government expanded administration over forests, particularly pine forests, across the coasts and islands of southwestern Korea. The key vehicle for the expansion was the military. Due to wartime and postwar exigencies, the military became the late Chosŏn state's primary organ for management of wood resources for state purposes. Furthermore, the growth of pine-centric state forests and shifts in military priorities would significantly reshape Korean ecologies.