many countries go with war with each other for many reasons, one reason could be wanting to take power of that country and then fight over land and or resources, for example hong kong and china. Hong kong used to be owned by another country and then that country went to china and was like
we will give u back hong kong in 100 years. And china was like aight. Fast forward 100 years and then the people in hong kong were like
Yeah I dont rlly like china I dont wanna be with them... ANd then CHina was like No I OWN YOU NOW B)
and yeah a bunch of protests happened and people died