In the ensuing period, the western powers did not stop exerting pressure. In 1875, Japan dispatched the battleship Unyo Maru to attack Ganghwado and Yeongjongdo Islands, demanding that Joseon open its doors to foreign trade missions. Ultimately, Joseon was forced to sign the highly unequal, one-sided Ganghwado Treaty with Japan in 1876 under the threat of force. Subsequently, imperialist powers, including Japan, vied with each other to pillage Joseon’s resources. In 1897, Joseon changed its name to Imperial Korea and pushed ahead with reforms and the open-door policy, but it was too late.

Japan soon won major victories in its wars against Qing China and Russia, emerged as a strong power in Northeast Asia, and took steps to annex Joseon. Many Korean patriots, including Ahn Jung-geun, resisted such a plan, but to no avail. In August 1910, Imperial Korea became a Japanese colony.