Abstract
During the Late Joseon dynasty, abandoned mountain fortresses were urgently repaired for the operation of foothold mountain fortresses in Gyeongsang-do, during the Japanese Invasion of Korea in 1592 and immediately after the Qing Invasion of Korea in 1636. Immediately after the Qing Invasion of Korea, an external fortress wall was built and added to each of Cheonsaeng Fortress and Geumo Fortress to establish a system of protecting locals inside a fortress at important locations for border defense against Japan in the Yeongnam region. Cheonseng Fortress, however, did not have sufficient geographical and protection conditions as a mountain fortress for protecting people inside it; thus, Gasan Fortress was newly built to replace Cheonsaeng Fortress. Geumo and Gasan Fortresses were used in border defense against Japan during the period from King Injo's reign to the end of Joseon Dynasty, because the fortresses served the purpose of defending Nakdonggang River and middle roads located at important roads along the border in the Yeongnam region and because it was possible to quickly repair and use their existing fortress walls and internal facilities, such as middle fortress walls and ponds, that were constructed for long-term protection of locals inside the fortress. In addition, it was found, in this study, that a continuous discussion on how to supplement fortresses led to the reinforcement and improvement of fortress facilities and fortification technology through the application of major strengths of Chinese (Ming) and Japanese fortress systems.