By 1905 Japan had thwarted Chinese and Russian bids for influence over the Korean Peninsula and felt comfortable in demanding of Korea a relationship to her benefit. The 1905 Taft-Katsura agreement in effect gave tacit U.S. approval to the Japanese colonization of the peninsula in exchange for Japanese recognition of U.S. influence over the Philippines. Without opposition in Korea, in November 1905 Japan concluded a treaty with King Kojong, making Korea a protectorate and giving herself control over Korea’s foreign relations and external matters. The Japanese resident general also slowly took over internal affairs. With the forced abdication of the king in 1907, his son Sukjong took the throne. Japan pressured him to abdicate three years later and formally annexed the country in April 1910.

Quote from: koreanhistory.info

Wikipedia

Righteous armies, sometimes called irregular armies or militias, have appeared several times in Korean history, when the national armies were in need of assistance.

During the long period of Japanese invasion and occupation from 1890 to 1945, the disbanded imperial guard, and Confucian scholars, as well as farmers, formed over 60 successive righteous armies to fight for Korean freedom on the Korean peninsula. These were preceded by the Donghak movement, and succeeded by various Korean independence movements in the 1920s and beyond, which declared Korean independence from Japanese occupation.

For at least 13 years after 1905, small irregular forces, often led by regular army commanders, fought skirmishes and battles throughout Korea against Japanese police, armies, and underworld mercenaries who functioned to support Japanese corporations looting Korea, and as well armed Japanese settlers who seized Korean farms and land. In one period, according to Japanese records in Boto Tobatsu-shi (Annals of the Subjugation of the Insurgent), between October 1907 and April 1908, over 1,908 attacks were made by the Korean people against the invaders.

The Righteous Army was formed by Yu In-seok and other Confucian scholars during the Peasant Wars. Its ranks swelled after the Queen’s murder by the Japanese troops and Koreans. Under the leadership of Min Jeong-sik, Choe Ik-hyeon and Shin Dol-seok, the Righteous Army attacked the Japanese army, Japanese merchants and pro-Japanese bureaucrats in the provinces of Gangwon, Chungcheong, Jeolla and Gyeongsang.

Choe Ik-hyeon was captured by the Japanese and taken to Tsushima Island where he went on hunger strike and finally died as a martyr　in 1906. Shin Dol-seok, an uneducated peasant commanded over 3,000 troops. Among the troops were former government soldiers, poor peasants, fishermen, tiger hunters, miners, merchants, and laborers.
In 1907, the Righteous Army under the command of Yi In-yeong massed 10,000 troops to liberate Seoul and defeat the Japanese. The Army came within 12 km of Seoul but could not withstand the Japanese counter-offensive. The Righteous Army was no match for two infantry divisions of 20,000 Japanese soldiers backed by warships moored near Inchon.
The Righteous Army retreated from Seoul and the war went on for two more years. Over 17,000 Righteous Army soldiers were killed and more than 37,000 were wounded in combat. Unable to fight the Japanese army head-on, the Righteous Army split into small bands of partisans to carry on the War of Liberation in China, Siberia and the Jangbaik Mountains in Korea. The Japanese troops first quashed the Peasant Army and then disbanded what remained of the government army. Many of the surviving guerrilla and anti-Japanese government troops fled to Manchuria and Siberia and carried on their fight.

Source: Wikipedia, published under the GNU FDL. Retrieved 2014-03-08