https://en.wikipedia.org/wiki/Battle_of_Osan
The Battle of Osan (Korean: 오산 전투) was the first engagement between the United States and North Korea during the Korean War.On July 5, 1950, Task Force Smith, an American task force of 540 infantry supported by an artillery battery, was moved to Osan, south of Seoul, the capital of South Korea, and was ordered to fight as a rearguard to delay the advancing North Korean …