World War One: It begins with the MAIN causes and triggered by one event.
Crash Course: WW1
https://www.youtube.com/watch?v=_XPZQ0LAlR4
https://www.youtube.com/watch?v=Cd2ch4XV84s
https://www.youtube.com/watch?v=_pFCpKtwCkI
Crash Course: WW1
https://www.youtube.com/watch?v=_XPZQ0LAlR4
https://www.youtube.com/watch?v=Cd2ch4XV84s
https://www.youtube.com/watch?v=_pFCpKtwCkI