Eventually, regent Daewongun, believing the General Sherman to be a French Navy warship on a punitive mission to avenge the deaths of Catholic priests in Korea, ordered Pyongan Province governor Bak Gyusu to inform the crew that if they did not leave Korean waters they would be executed.

Korean diplomat Bak Gyusu attempted to negotiate for his release, while a crew of civilian onlookers gathered around the General Sherman, attacking the merchant ship in anger.

These policies remained in place during the 19th century, a period which saw the rapid increase in Western imperialism in Asia, including the Opium Wars which led to the opening of Qing China to foreign trade.

In response to these developments and what Joseon royalty perceived as a subversive religion, regent Heungseon Daewongun initiated a series of persecutions of Korean Christians in 1866 in which 8,000 were killed, including several French missionaries.

[1][4] Determined to force the Korean government to end its isolationism, the SS General Sherman, an armed merchant schooner owned by Boston businessman W. B. Preston, made plans to travel to Korea.

The crew of the General Sherman consisted of Captain Page and Chief Mate Wilson (both Americans), English supercargo George Hogarth and thirteen Asian crew-members, which included Chinese sailor and interpreter Chao Ling Feng, two pilots from Shandong and ten sailors from Beijing, Malaya and South China (who were possibly former soldiers in service of Henry Andres Burgevine).

[1][6][7] After receiving reports of the General Sherman and its voyage, Daewongun believed the merchantman to be a French Navy warship on a punitive mission to avenge the deaths of Catholic priests in Korea.

[1][7] A crowd of civilian onlookers, which had gathered near the stranded merchantman, grew so angered by the unfolding situation that they began attacking the General Sherman with arrows, stones, and Hwacha rockets.

The Koreans initially attempted to destroy the General Sherman by constructing an improvised turtle ship, which was protected by metal sheeting and cowhides and equipped with a concealed cannon.

However, the turtle ship's cannon proved unable to penetrate the armor of the General Sherman, and return fire killed a crewmember of the Korean warship.

[1][4] After the first attack failed, the Koreans then roped together three small boats loaded with firewood, saltpeter, and sulfur, lighting them on fire, and sent them drifting towards the General Sherman.

The New York Times claimed that the expedition would produce a "Detailed Account of the Treacherous Attack of the Coreans on Our Launches" and deliver "Speedy and Effective Punishment of the Barbarians".