Probably one of the weirdest wars in modern history, the Sino-Vietnamese, was when the People's Republic of China invaded Soviet Supported Vietnam even though they all shared the same ideology they still fought a war in 1979, a couple years after the end of the famous Vietnam War which saw the American's retreat out of Vietnam and saw South Vietnam fall to the Communist North.
![](https://i.ytimg.com/vi/foBYcrtXhO0/mqdefault.jpg)