This paper newly interpreted the article of Nihonshoki(⽇本書紀) to reveal the reality of the discussions that King Wideok(威德王) was responsible for losing the war, and also estimated that Prince Yeochang(餘昌) built a fortress of Gutamora(久陀牟羅) in the area of Simcheon-myeon, Yeongdong-gun, Chungbuk during the Battle of Gwansan Fortress. Prince Yeochang(King Wideok), who ascended the throne after the defeat in the Battle of Gwansan Fortress, was held accountable for the defeat by many of his ministers. Therefore, previous studies have generally understood that Prince Yeochang attempted to fight Gwansan Fortress Battle in defiance of the opposition of the senior ministers. However, considering that the actual subject of the war was Prince Yeochang's father, King Seong(聖王), and that he had been preparing for the war with Silla for about two years, it should be considered that the opposition point of the senior minister was not before the war with Silla, but during the war with Silla. In addition, if the article on the 15th year of Kinmei-Record on Nihonshoki is interpreted in order, it can be seen that after the fall of Gwansan Fortress, Prince Yeochang attempted additional attacks and eventually moved the military to Gutamora. Therefore, Yeochang‘s responsibility can be attributed to the military action that went all the way to Gutamora, ignoring the opposition of the senior ministers after the capture of Gwansan Fortress. It is interpreted that many ministers held King Wideok responsible for the war's defeat, as such military actions killed King Seong and ultimately defeated the Battle of Gwansan Fortress.
On the other hand, Baekje‘s attack on Gwansan Fortress in 554 began as a “revenge against the re-emphasis on the Han River basin”, so it can be said that it was carried out with a goal as important as the restoration of Hanseong(漢 城). In this regard, after the successful attack on Gwansan Fortress, Prince Yeochang joined the rear troops, beat the counterattack of Silla's Sangjujeong(新州停) and the central army, and further advanced to Gutamora despite opposition from senior ministers to conquer Silla. It is estimated that Gutamora, which was additionally marched at that time, is the area of Simcheon-myeon, Yeongdong-gun, Chungbuk, where military pressure was possible on Chupungryeong Road(秋⾵嶺路) and Hwaryeong Road(化嶺路). One of the reasons for this estimation is that the story of the blood-stained valley of Baekje-army and the death of King Seong is told in this area. However, Baekje's troops were dispersed due to the advance to Gutamora, which was carried out despite the opposition of the senior minister, and as a result, King Seong, who was moving from Okcheon, was killed and Baekje's troops were defeated. Therefore, it is understood that the responsibility for the defeat of Gwansan Fortress, which was later raised against King Wideok, was a military act that hastily decided to advance additional troops in defiance of the opposition of the senior minister.