After the opening of Korea’s ports in 1876, foreign powers entered the country, and Japan in particular gradually began to reveal its imperial ambitions toward Korea. After the Assassination of Empress Myeongseong by the Japanese in 1895, a righteous army led by Confucian scholars, who defended orthodoxy and rejected heterodoxy, fought against the Japanese. The Righteous Army of Gyeonggi-do Province, raised in 1896, was based in Namhansanseong.
The righteous army of Gyeonggi gathered near Namhansanseong on February 23, 1896 and joined the righteous army of Icheon in occupying the fortress on February 28. Later, they planned to advance on Seoul, but Kim Gwi-seong, after being captured and questioned by the government army, revealed to them that the western wall of Namhansanseong had been badly damaged. On hearing this, the government army advanced immediately to Namhansanseong and captured it, and the righteous army abandoned its plan to advance on Seoul.
Japan disbanded the Joseon Army on August 1, 1907 and recovered all its weapons and ammunition. At this time, the Japanese military promptly destroyed all the weapons and ammunition kept at the temples in Namhansanseong. On March 27, 1919, an independence movement against the Japanese colonial occupation emerged at Namhansanseong as an extension of the March 1st Movement.
The movement began with the raising of torches at Namhansanseong at dawn and chants for national independence. In the morning, some 300 inhabitants of Dandae-ri, Tan-ri, and Sujin-ri in Jungbu-myeon, Gwangju gathered together in the valley below the south gate of Namhansanseong and chanted for the independence of Joseon, and then entered the fortress and continued their demonstration at the local myeon office.
In the 1930s, Namhansanseong emerged as a center of the anti-Japanese national movement, which was led by socialist groups at that time. One such socialist anti-Japanese national independence movement group, the Namhansan Labor Association, was formed in 1930 by Seok Hye-hwan, Jeong Yeong-bae, and others in Sanseong-ri, Jungbu-myeon, within the precincts of the fortress. They strove to educate workers and farmers (about social issues), but they soon went to ground due to oppression by the Japanese police.
Several years later, however, they reorganized the group as the Gwangju Cooperative and continued with their activities, before establishing the Gwangju Communist Party Council in December 1934. They gathered at the labor union hall once a month to hold lectures and run a night school for workers, and also produced and distributed propaganda materials and expanded the group to Yeongdeungpo, Seoul and Incheon.
Meanwhile, in January 1936, one of its members accidentally dropped a material related with the group in the street and fell into the hands of the Japanese police, which led to the group’s collapse. It is noteworthy that the independence group formed in Namhansanseong sent its members to Yeongdeungpo and Incheon, which were densely populated factory areas at that time.