The Battle of Gwansanseong (管山城 戰鬪) was a battle in 554 in which the combined forces of Silla, Baekje, Gaya, and Wa fought at Gwansanseong (管山城, present-day Okcheon, North Chungcheong Province). In this battle, the Silla army annihilated the combined forces of Baekje, Gaya, and Wa, and killed King Seong of Baekje.
Background
In 551, Baekje and Silla, which had formed the Alliance between Silla and Baekje (433–553), learned that Goguryeo was in great internal turmoil. Seizing the opportunity, they attacked Nampyeongyang and took ten commanderies north of Jukryeong. Having secured the area north of the Han River, Silla established commanderies and counties and built up its defensive system. It then refused Baekje's request to advance north again. Goguryeo thereupon asked Silla, which was then in alliance with Baekje, for peace, and in 552 a nominal armistice was concluded between Silla and Goguryeo.1
This situation also appears in the Nihon Shoki. In May 552 or 553, Baekje sent Mongnigeumdon (木刕今敦), Central Deogsol, and Asabida (阿斯比多) of the Naebu (河內部) to Japan. They reported that Goguryeo had made peace with Silla and intended to attack "Baekje and Imna," and that Baekje was planning a preemptive strike.2
Meanwhile, King Seong of Baekje, whose diplomatic relations had become isolated, gave up the area south of the Han River and withdrew his troops. King Jinheung of Silla then dispatched troops in July 553, secured the area south of the Han River, and established Sinju (新州), with Sinju-jeong (新州停) under it. The Silla–Baekje alliance, however, was broken.
In September 553, King Seong sent envoys to Wa to request troops. In October of that year, he had his daughter become a secondary consort (小妃) of King Jinheung of Silla. In July 554, after Wa troops arrived, he ordered Crown Prince Buyeo Chang to mobilize Wa and Gaya forces and attack Silla. In the Battle of Gwansanseong, the Baekje army was badly defeated and King Seong was killed, and Baekje remained an enemy of Silla from then on.
Outcome
As mentioned above, just as in the times of King Asin in 400 and 404, Crown Prince Buyeo Chang commanded Baekje's main army and was also accompanied by reinforcements from Gaya and Wa. The Nihon Shoki, in the Kinmei chronicle (欽明紀), records that the forces of Mulbu Makgi-buryeon (物部莫奇武連), the Eastern Governor (東方領), were sent ahead to attack Hamsanseong (函山城; 管 and 函 have the same meaning). Gwansanseong was a strategic point connecting to the lower Han River region that Silla had newly occupied. On the 9th day of the 12th month, at the hour of rooster (酉時), the combined forces set fire to Gwansanseong and captured it. At that time, Silla's Gakgan Udeok (于德) and Ichan Tamji (耽知) led troops against the Baekje army, but they were all defeated by the combined forces led by Buyeo Chang, and a combined forces fortress was finally built at Gutamora (久陀牟羅).
King Jinheung ordered Silla's general Kim Muryeok to dispatch reinforcements. The Silla reinforcements heading for Gwansanseong captured King Seong at Gucheon (狗川) as he was traveling toward the Great Headquarters (大本營) in Silla territory. Then Gogan (高干)3 Dodo (都刀), a Bijang (裨將)4 from Samnyeonsan County (三年山郡), executed King Seong of Baekje.56
Evaluation
Many studies have regarded the Battle of Gwansanseong as a dramatic victory for the Silla army, and it is considered the established view that the balance of power between Silla and Baekje was completely reversed in this battle, after which Baekje went into decline. In Discovery of War (전쟁의 발견), Professor Lee Hee-jin argues that in the early stage of the Battle of Gwansanseong, Baekje held a slight advantage, and that the record in the Nihon Shoki conveys content closer to the facts than the account of the battle in the Samguk Sagi. King Seong never acted together with the main Baekje army deployed at Gwansanseong from beginning to end. The fifty men whom King Seong took with him, according to the Samguk Sagi, were his bodyguard unit moving close beside him and his principal attendants. It is hard to imagine that, in the battlefield where a major battle had just been fought, a night raid could be carried out with only fifty men, and it is difficult to regard the fact that he brought his close attendants as evidence that he had moved with "war" in mind from the start. Rather, the natural interpretation is that he was coming to Gwansanseong from the rear with his guards, after the fortress had been captured by the main Baekje army led by Crown Prince Chang, either to take part in the war directly or to resolve postwar matters. This happened even though, right after the Battle of Gwansanseong broke out, Sinju Governor Kim Muryeok was hurriedly leading reinforcements to counterattack the combined forces.
Regarding the damage suffered by Baekje as well, the Samguk Sagi states that "four Jwapyeong (佐平) and 29,600 soldiers were beheaded, and not a single horse returned,"7 and scholars have explained the extent of Baekje's damage by citing the figure of 30,000, which was large by the standards of the time, as the record of the annihilation at Gwansanseong in the Samguk Sagi. However, the same work, in volume 41, Biography 1, the first part on Kim Yu-sin, says: "His grandfather Muryeok became the Commander-in-Chief of the Sinju Route Army (新州道行軍摠管), and once led troops, captured the King of Baekje and four of his generals, and beheaded more than 10,000 men,"8 which shows a discrepancy in numbers. Regarding this, it is possible to view the record of more than 10,000 as the achievement of Kim Muryeok's unit alone, and the figure of 29,600 as the total when the achievements of other Silla forces were added to it. However, once the Silla forces led by Tamji and Udeok had been defeated by the combined forces, the only Silla force that could confront the Baekje, Wa, and Gaya combined army was Kim Muryeok's unit, and it was almost impossible for other Silla units besides Kim Muryeok's to gather in strength sufficient to achieve results equal to 10,000 men. The Samnyeonsan Fortress forces led by Bijang Dodo, who would behead King Seong himself, could only be mobilized from areas near the battlefield, so they cannot be regarded as a major force either in quality or quantity.9
Moreover, looking at the process of rewarding meritorious service in Silla after the Battle of Gwansanseong, the conduct of Gakgan Udeok, Ichan Tamji, and Sinju Governor Kim Muryeok of the Silla command differs greatly. In particular, Silla's Ichan Tamji, who fought against the Baekje army at Gwansanseong, had participated in the conquest of Goguryeo in the 12th year of King Jinheung's reign with the rank of Jabchan. Yet after the Battle of Gwansanseong, his name is hard to find in the Samguk Sagi, whereas Kim Muryeok advanced steadily afterward, and his descendants held key posts in the Silla court and enjoyed prosperity. This shows the possibility that Tamji achieved little of note at Gwansanseong compared with Kim Muryeok, and that he may have been removed from office for responsibility for the defeat by the combined forces. From this perspective, Tamji and Udeok achieved little compared with Kim Muryeok, and there is no room to assume that the Silla forces at Gwansanseong combined with Kim Muryeok's troops to launch a counterattack against the combined forces.
Kim Muryeok's army, stationed at Sinju, could not directly take part in the Battle of Gwansanseong because of its northern military position, and was instead dispatched after Gwansanseong had fallen. On its way to Gwansanseong, Kim Muryeok's unit gathered and incorporated Silla troops from the surrounding area, and the soldiers of Samnyeonsan Fortress were one of the units that joined in that process. Although the Silla forces knew in advance of King Seong's journey to Gwansanseong, set an ambush, and captured and killed him, there are no concrete records remaining on how King Seong's movements came into Silla's hands, or, even if they did, how the Silla forces could have guarded the route King Seong traveled with exact timing. Therefore, this cannot be determined.10
The damage that the Baekje army suffered at the Battle of Gwansanseong can be said to have been greater in its political and social aspects than in its military aspects. In the Nihon Shoki, the war was strongly opposed by Baekje's influential aristocrats, represented by the "gilo" (耆老) or "nosin" (老臣), and it was Chang, who commanded the Baekje army at the front lines, who pushed the war forward. To expand the foundation of royal authority in the face of aristocrats who opposed the war, King Seong and Crown Prince Chang had to make their attack on Silla succeed. However, after Gwansanseong had already fallen, King Seong unexpectedly died in a Silla ambush, and not only King Seong but also the aides who would have supported and carried out his policies, represented by the "four Jwapyeong" in the Samguk Sagi, lost their lives together with him. Conversely, the voices of the aristocrats who had originally opposed the war grew even stronger after the Battle of Gwansanseong, and royal authority in Baekje came under threat. Furthermore, Baekje's policy, which had given weight to war against Goguryeo, shifted toward war against Silla after the Battle of Gwansanseong, and afterward Baekje lost its influence over the Gaya region, and the Gaya region was annexed by Silla.11
Footnotes