Korean invasion of Manchuria
The Korean Empire invasion of Manchuria was an invasion of Manchuria (Northeast China, then ruled by the Qing dynasty) by the Korean Empire. The attack began on 11 August 1902, when Gojong of Korea sent Yi Bum-yun to Jiandao (also called "Gando" in Korea) as an observer.
Source: Wikipedia — Korean invasion of Manchuria (CC BY-SA 4.0)