In 1583, a year before his death, Yul-Gok proposed that the government train and equip a 100,000-man Army Reserve Corps. This suggestion, like others he recommended, was undermined by minor officials who were caught up with the east-west political conflict within the government. It was unfortunate that this suggestion concerning national security was never allowed to be implemented. Nine years later, the Korean military forces and government officials failed in their resistance against the invasion by the Japanese army of Hideyoshi, resulting in the occupation of Korea.
Although never really permitted to see his theories and systems applied due to the political environment of the time, Yul-Gok nonetheless was an extraordinary philosopher. Long after his death in 1584, Yul-Gok has continued to have a profound effect Upon Korea and the world as a result of his lifelong dedication to Confucianism and theory of government.