|United States|| Yi dynasty|
|Casualties and losses|
Conflict first erupted between the two sides when the conservative faction of the Han state-council, led by General Mé Ling and Empress Ming, decided to assault a group of American troops stationed in Hanyang. Seeking to reestablish the abandoned isolationist foreign policy and returning the Yi dynasty to its pre-opening enclosure, the conservative faction objected to the peace terms proposed by the Americans. Furthermore, the conservative faction pressured the central government to nullify previous unequal treaties signed between it and the United States, denying the Americans access to Hani and robbing them of their extraterritorial rights.
Refusal by the Hans to accept its peace terms and to reinstate friendly relations prompted the United States to use this as a casus belli to justify the annexation of the strategically important Han archipelago. Despite some rigorous modernisation prior, its core regions quickly succumbed to American occupation, specifically the Central Rusan plain, the areas surrounding the Hanyang Bay, and the Gaya Valley. However, in mountainous regions, resistance was thick, lengthening the war by an additional three years.
The war effectively ended on March 26, 1904, and ended with the incorporation of the Yi dynasty as a protectorate as per the Treaty of Hanyang. The treaty forced it to give its suzerainty to the United States, while maintaining nominal sovereignty, and ending its traditional relationship with the Chinese. Guerrilla fighting among some remote regions continued, but posed little threat to the American hegemony over the archipelago.