Warfare drove depletion of forests and forest management in the early modern world, as states required increasing control over timber resources to support their growing militaries. East Asia was no exception. Scholars have shown how the Chosŏn Korean state tightened control over forests via its navy during the seventeenth century, following invasions by the Japanese hegemon Toyotomi Hideyoshi between 1592 and 1598. This devastating conflict between China, Korea, and Japan was the largest war of the sixteenth-century world. The vast size of the Japanese invasion fleets, the naval battles that were fought along the Korean coastline, and the building of fortresses throughout the occupied parts of the peninsula meant timber was of paramount significance during the war. The Korean island of Kŏje was of particular strategic importance both for its location on the southern coast facing Japan and for the high-quality pine lumber produced there. This article explores the exploitation and protection of the forest environment of Kŏje during the war, focusing on a four-month period at the start of 1597 when tensions came to a head. The case of Kŏje shows the efficacy of direct management of forests by naval forces, as well as the results of a clash between early modern Chinese, Japanese, and Korean state cultures of timber control. The management of Kŏje’s timber by the Chosŏn navy during the war also helps explain why it was the navy that was later given administrative responsibility for managing forests in the postwar period.