This article attempts to establish a comprehensive understanding of the many international wars that beset East Asia from the late sixteenth to the early seventeenth century. These wars can be summarized as attempts by newly unified polities in Manchuria and Japan to subjugate the “Chinese cultural sphere” represented by Chosŏn Korea and Ming China—attempts that were ultimately successful. Although the aggressors in the Imjin War on the one hand and the Chŏngmyo-Pyŏngja Wars on the other were different and did not mutually influence each other, they showed similar logic in trying to legitimize their invasions of Chosŏn. By comparing documents produced before and during the conflicts by the Japanese and the Manchu, this article will ascertain how both sides justified their invasions and how they tried to impose this historical memory on the invaded country, Chosŏn. By retracing the discourse of a “just war” that was developed in pre-modern East Asia, this study shows how both Manchu and Japanese documents regarding the foreign invasions refer to ancient Chinese concepts of “punitive expedition” (zhengfa) and Heaven (Tian), which are either used in different ways (in the case of the former), or in broadly similar ways (in the case of the latter) by both sides. The relevant documents, which were composed either during the war or shortly after, show how both sides employed similar strategies to try and argue that their invasions were cases of righteous wars. Rather than taking Chosŏn’s experience of being invaded as unique and absolute, this article tries to reevaluate this experience from a world history perspective, and makes a case for seeing these conflicts as part of a series of interconnected events that took place at a turning point in East Asian history.