Mostly, I pointed out historic facts without judging their worthiness.

Having said that, there have been many historical cases where war broke out because one side did something that threatened the other's existence or prosperity, even if there were no overt military attacks yet.

Sometimes there were violent acts that weren't military in nature. For example, WW I broke out after an assassination, which may even have been a false flag action (it's been decades since I read about it so my memory isn't so clear).

The thing is, sometimes waiting for the other side to actually attack is too dangerous and you can't afford to take that risk, of letting your enemy choose the time and place where war will start.