Ganghwasanseong Fortress
Fortress that served as Goryeo capital during Mongol invasions.
Ganghwasanseong Fortress (강화산성; 江華山城) is a historic defensive complex on Ganghwa Island in Incheon, South Korea. It was first built in 1232 as the new capital of the Goryeo kingdom after the court fled Kaesong during the Mongol invasions. The original fortress was later torn down under a peace agreement with the Mongols, but sections were reconstructed and remained in military use into the 1900s.
The original design featured three concentric walls made of rammed earth, modeled after the walls of Kaesong. The innermost wall enclosed the palace grounds, while the outermost wall stretched along the island’s eastern coast. This layout was meant to block invasions from the mainland. During the Joseon period, the inner and outer walls were rebuilt—this time in stone—but the middle wall was never restored.
Because the fortress guarded the mouth of the Han River, it stayed strategically important. It was damaged during the French expedition to Korea in 1866 and the United States expedition in 1871. The Japan–Korea Treaty of 1876 was signed here. The inner fortress was named a Historic Site in 1964, and major restoration work began after 1977. The outer walls received their own Historic Site designation in 2003.
**History**
The Goryeo court moved to Ganghwa Island in 1232 under the direction of military leader Ch’oe U, who controlled the government during King Gojong’s reign. Kaesong’s population at the time was about 100,000, so extensive development was needed on the island to house the relocated court. Construction was likely overseen by the Jangjakgam, with around 2,000 soldiers recorded as laborers, possibly joined by civilians. Artisans from the capital probably produced roof tiles at the site. Work accelerated in January 1234.
The fortress’s three walls—inner, middle, and outer—were designed to repel Mongol coastal attacks and protect the palace. The outer wall was likely built first, then the middle wall. All walls were demolished as part of the peace deal after Goryeo surrendered to the Mongols and the capital returned to the mainland.
The Sambyeolcho Rebellion began on Ganghwa in June 1270. The outer walls may have inspired the Hwanhaejangseong walls built by the Sambyeolcho on Jeju Island, which in turn may have influenced the Genkō Bōrui in Kyushu, Japan.
Quick Facts
- Location
- San 3, Gukhwa-ri, Ganghwa-gun, Incheon
- Area
- 789204 m2
- Built
- 1232
- Built For
- Goryeo dynasty
Facts from the source article.
Lore & Background
During the Mongol invasions of Korea, the Goryeo court moved to Ganghwa Island in 1232. This decision was made by Ch'oe U, a military leader who controlled the government during the reign of King Gojong of Goryeo. The population of the former capital, Kaesong, was around 100,000 at that time, and significant development was needed on Ganghwa to accommodate all those moving to the relatively safe island. Construction of the new capital was likely supervised by the Jangjakgam, with around 2,000 soldiers recorded to have been involved. The fortress was a multi-layered system with inner, middle, and outer walls, designed to resist potential Mongol coastal invasions. All of the walls were demolished as part of the peace deal after the Koreans surrendered to the Mongols and the capital moved back to the mainland.
The Joseon dynasty rebuilt the inner fortress, although it was destroyed again during the 1636–1637 Qing invasion of Joseon. It was again rebuilt, and slightly enlarged, during the rule of Sukjong of Joseon. The outer wall was repaired in 1618 during the rule of King Gwanghaegun, but was also destroyed during the Qing invasion. The outer wall was rebuilt using stone under Sukjong, with new fortifications being constructed along it. The fortress was damaged again in 1866 during the French expedition to Korea and in 1871 during the United States expedition to Korea. The Japan–Korea Treaty of 1876 was signed at the site. The inner fortress was designated a Historic Site in 1964, and the outer walls were designated a separate Historic Site in 2003.
Reader's Guide
Ganghwasanseong Fortress holds significant historical importance as the relocated capital of the Goryeo kingdom during the Mongol invasions, demonstrating the kingdom's strategic response to external threats. Its triple-wall design, reflecting the Kaesong city walls, illustrates the adaptation of capital defenses to an island location. The fortress's continued use and rebuilding through the Joseon period, including after the Qing invasion, underscores its enduring military value in protecting the Han River approach. The site's involvement in 19th-century conflicts with France and the United States, as well as the signing of the Japan–Korea Treaty of 1876, marks it as a key location in Korea's interactions with foreign powers. The designation of the inner fortress and outer walls as separate Historic Sites in 1964 and 2003 respectively, along with extensive restoration work since 1977, highlights its recognized cultural heritage. The fortress also provides insights into historical construction techniques, with the middle wall preserving original Goryeo rammed earth construction, and the outer wall revealing information on fort building methods through archaeological remains.
Did You Know?
- The fortress was first constructed in 1232 to serve as the capital of the Goryeo kingdom during the Mongol invasions.
- The original structure consisted of three concentric rammed earth walls, reflecting the design of the Kaesong city walls.
- The Japan–Korea Treaty of 1876 was signed at the Yeonmudang pavilion near the west gate.
- The outer wall was originally built from 1233 to 1237 and stretched 23 kilometres along the island's eastern coast.
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