Western Disturbance in the Shinmi Year) or simply the Korean Expedition, was an American military action in Korea that took place predominantly on and around Ganghwa Island in 1871.

Frederick Low, the American ambassador to China, sent the mission to ascertain the fate of the merchant ship General Sherman, which had gone missing while visiting Korea in 1866.

[2] Korean officials had sent letters holding the Americans responsible for unlawfully sending warships into their territorial waters, and also explaining to Low what had happened to the General Sherman.

[4] The American expedition consisted of about 650 men, more than 500 sailors and 100 Marines, as well as five warships:[5] Colorado, Alaska, Palos, Monocacy, and Benicia.

Embarked aboard Colorado was Rear Admiral John Rodgers, and Frederick F. Low, the United States Ambassador to China.

When they inquired about the General Sherman incident, the Koreans were initially reluctant to discuss the topic, ostensibly to avoid having to pay recompense.

This gesture was misinterpreted; Korean policy at the time prohibited foreign ships from sailing on the Han River, which led directly to the capital city of Hanyang, modern-day Seoul.

The total number killed was 243 Koreans and three Americans; McKee, Seaman Seth Allen, and U.S. Marine Corps Private Denis Hanrahan.

[17] Following the military operations of 10–12 June, the United States Asiatic Squadron stayed at anchorage off Jakyak Island[clarification needed] until 3 July, when they left for China.

In fact, these events led the regent Daewon-gun to strengthen his policy of isolation and issue a national proclamation against appeasing foreigners.

In 1876, Korea established a trade treaty with Japan after Japanese ships approached Ganghwa Island and threatened to fire on Seoul.

Nine sailors (Chief Quartermaster Grace, Quartermasters Troy, Franklin and Rogers, Boatswain's Mate McKenzie, Ordinary Seaman Andrews, Carpenter Hayden, and Landsmen Lukes and Merton) and six Marines (Corporal Brown and Privates Coleman, Dougherty, McNamara, Owens, and Purvis) were awarded the Medal of Honor, the first for actions in a foreign conflict.