The Aggressive National Defense Posture Taken during the Reign of King Sejong of the Joseon Dynasty

This article will focus on the dispatch of expeditionary troops to defeat Japanese pirates whose headquarters were based on Daema Island (Tsushima Island in Jp.) and on military campaigns waged against the Jurchen tribes along the Pajeo River. It will examine King Sejong's political thought on conquest by focusing on the aggressive national defense security carried out against Daema Island and Pajeo River. King Sejong was Joseon dynasty's representative political leader and king of Confucian statecraft. This paper will also deal with the process of the Joseon dynasty's conquest of Daema Island from June 17, 1419 to July 6, 1419 and examine the following matters. First, what were the causes, processes, and consequences of the conquests? Second, despite Joseon dynasty having conquered Daema Island, part of Japan's territory, why didn't local war break out between Korea and Japan? Third, why was Joseon not able to annex Daema Island despite having attacked Japan with 17,285 soldiers and 227 warships? I will attempt to show how King Sejong's peculiar way of arriving at political judgment by engaging in constructive group discussions with the literati-bureaucrats, even those who opposed his ideas, contributed to the strengthening of the state during the formative years of the Joseon dynasty.