In 1875, the plan was put into action: the Un'yō, a small Japanese warship, was dispatched to present a show of force and survey coastal waters without Korean permission.

[4] The Daewongun was determined to continue Korea's traditional isolationist policy and to purge the kingdom of any foreign ideas that had infiltrated the nation.

[5] The disastrous events occurring in China, including the First (1839–1842) and Second Opium Wars (1856–1860), reinforced his determination to isolate Korea from the rest of the world.

[5] From the early-to mid-19th century, Western vessels began to make frequent appearances in Korean waters, surveying sea routes and seeking trade.

In June 1832, a ship from the East India Company, the Lord Amherst, appeared off the coast of Hwanghae Province seeking trade but was refused.

[5] In June 1846, three French warships dropped anchor off the coast of Chungcheong Province and conveyed a letter protesting persecution of Catholics in the country.

[5] In April 1854, two armed Russian vessels sailed along the eastern coast of Hamgyong Province, causing some deaths and injuries among the Koreans they encountered.

[clarification needed] The incident prompted the Korean government to issue a ban forbidding the people of the province from having any contact with foreign vessels.

In January and July 1866, ships manned by the German adventurer Ernst J. Oppert appeared off the coast of Chungcheong Province seeking trade.

[5] In August 1866, an American merchant ship, the General Sherman, appeared off the coast of Pyongan Province, steaming along the Taedong River to the provincial capital of Pyongyang, and asked permission to trade.

[11] During the aftermath of the Meiji restoration in late 1868, a member of the Sō daimyō informed the Korean authorities that a new government had been established and that an envoy would be sent from Japan.

Nonetheless, Commander Inoue ordered a small boat to launch and put ashore a party on Kanghwa Island to request water and provisions.

It gave extraterritorial rights to Japanese citizens in Korea, and forced the Korean government to open three ports to Japan:Busan, Incheon and Wonsan.