Ahn Chang-Ho was committed to preserving the Korean educational system during the Japanese occupation and was well known for sincerity and lack of pretense in dealing with others. A farmer's son, he abandoned traditional learning in his home town, Pyongyang, and studied for two years at a missionary school operated by the Salvation Army. He became a Christian and felt he could not hate the Japanese as men. He decided to seek a source of national strength and cultivate it to regain national independence and prosperity. 

To understand the significance of Ahn Chang-Ho's achievements, one must understand the oppressive climate throughout the Korean peninsula during the Japanese occupation (1904-1945). During the occupation, the Japanese tried to eradicate Korean culture, literature historical records, and education. As a result, many refugees fled to China, Manchuria, United States, and other countries. 

In 1894, at the age of 18, Ahn became a member of the Tongnip Hyophoe "Independence Association," which promoted independence from Japan and worked to reform domestic affairs and reduce dependence upon foreign countries. But the group's activities were interrupted by the conservative ruling class, so, Chai-pil, leader of the group, went into exile in the United States. This strengthened Ahn's belief that Koreans themselves were to blame their failures and thus victory must come from within. He returned to his home town and established the Chomjin School, the first private modern school established in Korea.

Among the first Koreans to emigrate to United States in 1902 were Ahn Chang-Ho and Rhee Syngman, who was later to become the first president of the Republic of Korea. Once in United States, Ahn Chang-Ho established groups within the Korean community in support of the independence of the Korean people. In 1903, Ahn organized a fraternity that became the Kungminhoe (Korean National Association), which inspired Korean immigrants toward a movement for national independence. The group published a newspaper called "Kongnip Shinmun."

Upon learning of the Japanese protectorate treaty enforced on Korea in 1906 following the Russo-Japanese war, Ahn returned home in 1907. He organized an underground independence group in Pyong--An Province called Shinmin-Hoe (New Peoples' Association). The Shinmin-Hoe was associated with Protestant organizations and was dedicated to promoting the recovery of Korean independence through the cultivation and emergence of nationalism in education, business, and culture. 

In 1908 the Shinmin-Hoe established the Tae-Song (large achievement) School in Pyongyang to provide Korean youth with an education based on national spirit. He ran a ceramic kiln to raise funds for the publications of books for young people. However, the political environment of the time was not conducive to the founding of such a school; the Japanese were in the process of actively banning education for Koreans. By denying the Korean children proper schooling, the Japanese wanted to ensure their illiteracy, thus essentially creating a class of slave workers.

Together with Yi Kap, Yang Ki-tak, and Shin Chae-Ho, he embarked on a lecture tour throughout the nation, warning of a national crisis incurred by the Japanese and urged the public to unite to resist the Japanese. Ahn repeatedly told Japanese leaders that Japan would profit much by keeping Korea as a friend rather than annexing Koreans and inviting their resentment.

By 1910 the Shinmin-Hoe had around 300 members and represented a threat to the occupation. The Japanese were actively crushing these types of organizations, and the Shinmin-Hoe quickly became a target of their efforts. In December of 1910 the Japanese governor general, Terauchi, was scheduled to attend the dedicating ceremony for the new railway bridge over the Amnok River. The Japanese used this situation to pretend to uncover a plot to assassinate Terauchi on the way to this ceremony. All of the Shinmin-Hoe leaders and 600 innocent Christians were arrested. Under severe torture, which led to the deaths of many, 105 Koreans were indicted and brought to trial. During the trial, the defendants were adamant about their innocence. The world community felt that the alleged plot was such an obvious fabrication that political pressure grew, and most of the defendants had to be set free. By 1913, only six of the original defendants had received prison sentences.

By this time, the Japanese had become fairly successful at detecting and destroying underground resistance groups. However, they were not successful in quelling the desire for freedom and self-government among the Korean people. The resistance groups moved further underground and guerilla raids from the independence groups in Manchuria and Siberia increased. 

The Japanese stepped up their assault on the Korean school system and other nationalistic movements. After the passage of an Education Act in 1911 the Japanese began to close all Korean schools. In 1913, the Tae- Song School was forced to close, and, by 1914, virtually all Korean schools had been shut down. This all but completed the Japanese campaign of cultural genocide. Chances of any part of the Korean culture surviving rested in the hands of the few dedicated patriots working in exile outside of Korea.

When Japanese governor-general Hirobumi Itoho was assassinated by Ahn Choong-gun (1879 - 1910), an independence fighter, Japan tightened its grip on Korean leaders. Finally Ahn exiled himself to Manchuria, then traveled to Siberia, Russia, Europe, and finally to the United States, along with Rhee Syngman. Rhee organized the Tongjihoe (Comrade Society) in Honolulu. In 1912, Ahn was elected chairman of the Korean National People's Association, which emerged as the supreme organization for Koreans abroad and played an active role in negotiations with the U.S. government. During this time, he established Hungsadan, a secret voluntary group of ardent patriots. 

Through these and other organizations an attempt was made to pressure President Woodrow Wilson into speaking in behalf of Korean autonomy at the Paris peace talks. Finally, in 1918, a representative of the Korean exiles was sent to these peace talks.

In 1919, when the Joseon Dynasty was forcefully absorbed into the Japanese Empire, Ahn started underground activities that focused on regaining Korean independence. He returned to Shanghai in April 1919 along with  Rhee Syngman and Kim Ku, where and became acting premier of a provisional government. They drew up a Democratic Constitution that provided for a freely elected president and legislature. This document also established the freedom of the press, speech, religion, and assembly. An independent judiciary was established and the previous class system of nobility was abolished. After trying in vain to narrow the differences of opinion between the leaders in Shanghai, he resigned from the post after two years.

Finally, on March 1, 1919, the provisional government declared its independence from Japan and called for general resistance from the Korean population. During the resistance demonstrations the Japanese police opened fire on the unarmed Korean crowds, killing thousands. Many thousand more were arrested and tortured.

Even after the Korean Declaration of Independence, Ahn Chang-Ho continued his efforts in the United States on behalf of his homeland. Ahn wanted to establish an ideal village for wandering Korean refugees in Manchuria and visited them in the 1920s. In 1922, he headed a historical commission to compile all materials related to Korea, especially the facts concerning the Japanese occupation. 

After a bombing incident launched by Yun Pong-gil, he was arrested by the Japanese, though he was not involved in the incident. His 23-year-long fight for national independence abroad ended with his imprisonment in Taejon in 1932. After a brief release from the prison, he was arrested again by the Japanese police. With failing health, he left the prison on bail only to die in a Seoul hospital on March 10, 1938.