Battle of Gwiju 1019: How Goryeo Won and Why It Matters

The Battle of Gwiju was a victory won in 1019 by the Goryeo army under Gang Gam-chan. Goryeo stopped the Khitan army's advance on the capital by defending Gaegyeong. Its forces then worked together at Gwiju to inflict a major defeat on the retreating army. Relations later stabilized through a peace agreement, and the battle is remembered as a turning point in the war.

This article follows the accounts in Goryeosa and Goryeosa jeoryo, checked in October 2026.

The Battle of Gwiju and the War Timeline

The decisive battle at Gwiju took place on the 1st day of the 2nd lunar month of 1019. The site is around present-day Kusong, North Pyongan Province, North Korea. The battle brought the third Khitan invasion, which began in 1018, to a close. The month and day follow the lunar dates in the historical sources.

The Battle of Gwiju was an individual battle and must be distinguished from the war as a whole. The victory at Heunghwajin did not end the Khitan advance. The defense of the capital and attacks on the retreating army followed. The date of the decisive battle can be confirmed in the relevant entry in Goryeosa jeoryo.

Why Did the Khitan Invade Again?

The third invasion arose from disputes over the 6 prefectures of Gangdong and the king's personal visit to the Khitan court. Such a visit meant the Goryeo king going in person to the Khitan emperor's court. After the second invasion, the Khitan demanded that this promise be fulfilled. They also continued to demand the return of the 6 prefectures of Gangdong.

Military pressure continued when Goryeo refused these demands. So Bae-ap's expedition in 1018 began amid this conflict. Goryeo still faced the possibility of another threat to its capital. Gaegyeong had, in fact, fallen during the earlier war in 1010.

The Role of a Commander-in-Chief with a Civil Official's Background

The commander-in-chief was a civil official who had passed the state examination. After placing first in the examination in 983, he took on major state responsibilities. During the war in 1010, he advised Hyeonjong to flee. He later also handled military affairs in the northeastern region.

His background as a civil official therefore does not mean that he lacked military experience. In 1018, he was appointed supreme commander and placed in charge of the entire Goryeo army. Deputy commander Gang Min-cheom assisted him and took part in the pursuit. His career and the background to his appointment are outlined in Uriyeoksanet's commentary on the historical sources.

Why Was Gaegyeong in Danger Despite the Victory at Heunghwajin?

The victory at Heunghwajin did not stop the advance of the entire Khitan army. Even after their defeat, Khitan forces continued south toward Gaegyeong. Goryeo forces responded by pursuing them, but separate preparations were also needed to defend the capital.

Goryeosa records that Goryeo forces blocked a waterway and concealed soldiers at Heunghwajin. When the enemy approached, they released the water, and the hidden troops attacked. Gang Min-cheom then attacked Khitan forces at Naegusan in Jaju. Jo Won also fought at Matan.

Winning a local battle and removing the threat to the capital were separate matters. Uriyeoksanet suggests that the Khitan army may have sought the king's surrender. This is an interpretation based on its route of advance. It must be distinguished from a statement directly confirming the Khitan commanders' intentions.

The Defense of Gaegyeong and the Arrival of Kim Jong-hyeon's Unit

The turning points in the campaign were the defense of the capital and the reinforcements at Gwiju. The successful defense of Gaegyeong thwarted the objective of the Khitan advance. Later, at Gwiju, the arrival of another unit changed the standoff.

The Defense of Gaegyeong and Scorched-Earth Measures

Hyeonjong moved residents from outside the city walls into the city. He also ordered grain removed from the fields. Scorched-earth measures prevent the enemy from using local food and supplies. These measures made it difficult for Khitan forces to sustain themselves around the capital.

Kim Jong-hyeon led 10,000 soldiers to defend Gaegyeong. Another 3,300 soldiers were sent from the northeastern region. Unable to capture Gaegyeong, the Khitan army turned north. Goryeo forces continued their attacks around Yeonju and Wiju.

The Reinforcements That Changed the Standoff at Gwiju

The arrival of Kim Jong-hyeon's unit at Gwiju is recorded as a turning point in the battle. At first, the two sides faced each other without either gaining victory. After the supporting troops arrived, Goryeo forces intensified their offensive. Goryeosa also records that wind and rain came from the south at this time.

Goryeo forces continued their pursuit toward Seokcheon and Ballyeong. Gwiju was a passage surrounded by mountains and valleys. Uriyeoksanet describes this terrain as favorable for blocking a retreating army. The sequence connecting Gaegyeong and Gwiju can be found in the commentary in the Chronology of Korean History.

Factors Behind the Victory at Gwiju

The victory can be explained as the result of coordination between the defense of the capital and the actions of field units. The tactics at Heunghwajin alone cannot adequately explain the entire war. The following table is an interpretation that groups events in the historical sources by their function.

Uriyeoksanet's commentary also identifies the transmission of battlefield information as a factor behind the victory. It also discusses the state's control over Gaegyeong's residents. These conditions allowed commanders' decisions to translate into military action. However, the sources examined do not allow the specific means of communication to be reconstructed.

Peace and Stable Relations After the Battle

Relations stabilized as a peace agreement followed the victory. Goryeo sent envoys to the Khitan to pursue peace. Hyeonjong's investiture and the use of the Khitan era name formed part of the diplomatic settlement. Investiture was the procedure through which an emperor recognized the status of another country's king.

Military victory and acceptance of diplomatic formalities could coexist. Even after winning the battle, Goryeo established diplomatic relations with the Khitan. The two states then maintained relations for a long period without major military clashes. Uriyeoksanet describes this as a key outcome of the war's end.

Continued peace did not mean an end to defensive preparations. Goryeo continued to improve defensive facilities in the capital and along the borders. Peace and stronger defenses thus proceeded together. This pattern can also be seen in Uriyeoksanet's textbook materials on Goryeo's foreign relations.

How to Read Troop Figures Separately for Each Battle

Troop numbers at the beginning of the war must not be treated as the numbers present at Gwiju. Each recorded figure refers to a particular time and group. Separate evidence is needed to establish troop strength after continued movements and battles.

These distinctions follow the narrative sequence in Goryeosa. Simply dividing the initial troop figures and presenting the result as the force ratio at Gwiju changes the scope of the figures. Nor can everyone other than those who returned be counted as killed in action. The context of the numbers can be checked against the original text of Goryeosa, volume 94.

Records and Interpretations

Facts stated in the records must be distinguished from later explanations. The historical sources also contain errors in personal names and approximate figures. Even when several records describe the same war, their dates and locations do not match completely.

What the Records Directly State

Goryeosa records the water attack at Heunghwajin and the reinforcements at Gwiju separately. Goryeosa jeoryo gives the month and day of the decisive battle at Gwiju. Liaoshi also records the defeat of Khitan forces fighting Goryeo.

However, the relevant entry in Liaoshi does not match the date of Gwiju exactly. The Korean History Database classifies it as an entry for the 12th lunar month of 1018. The battle locations are also given as Daha and Taha. The entry in Liaoshi therefore should not be assumed to be an on-site account from the same day.

Interpretations Presented in Historical Commentary

The National Institute of Korean History's commentary explains the victory primarily through the defense of the capital and cooperation between units. It connects the blow inflicted at Heunghwajin with the blocking of the retreat route at Gwiju. It also interprets long-term changes in relations, including the peace agreement after the war.

Wind and rain are one element of the battle conditions mentioned in the sources. That does not provide grounds to conclude that weather alone decided the outcome. The arrival of troops and the shift to an offensive also appear in the same record.

Errors in Personal Names and Remaining Uncertainties

The Khitan commander at the time was So Bae-ap. The relevant passage in Goryeosa gives the name So Son-nyeong. Uriyeoksanet's commentary explicitly identifies this as an error in the source. Reproducing the original name without checking it would misidentify the commander.

The records examined do not make it possible to establish the exact number of troops on the battlefield. Nor can all the detailed deployments at Gwiju be reconstructed. These gaps must not be filled with invented dialogue for commanders or scenes of operational meetings.

What This Battle Means for Readers Today

This battle shows the relationship between military achievements and diplomatic outcomes. The defense of the capital and the defeat of the retreating army were distinct processes. After the war, diplomacy followed to stabilize relations.

These distinctions are also useful when organizing historical information as data. Dates must indicate whether they follow the lunar calendar. Troop figures need a time and a clearly identified group. When correcting an error in a historical source, both the original wording and the grounds for correction must be retained.

Frequently Asked Questions

Were Gwiju and Heunghwajin the Same Battlefield?

They were different places. The tactic of blocking a waterway and then releasing the water is recorded at Heunghwajin. At Gwiju, Goryeo forces fought the retreating Khitan army.

How Did Troops Defending Gaegyeong Appear at the Battle of Gwiju?

Kim Jong-hyeon's unit was first dispatched to defend Gaegyeong. It is later recorded as joining the standoff at Gwiju. However, the passages examined do not describe its entire route.

Is It Accurate to Say That the Khitan Army Was Annihilated?

It is inaccurate if this means that not a single soldier survived. Goryeosa states that several thousand Khitan soldiers returned. The record's point is that the defeat was extremely severe.

Did Goryeo Maintain Diplomatic Relations with the Khitan Even After Its Victory?

Goryeo made peace with the Khitan after its victory. Hyeonjong's investiture and the use of the Khitan era name followed. Relations after the military victory can only be understood by also considering this diplomatic settlement.