For world leaders, it can be a tough decision to support the use of violence. 

Sometimes rival nations act belligerently, riots get disruptive, or underground networks of almost impossible to identify enemies use guerilla tactics to terrorize small locales in the hopes of provoking a disproportionate response. 

During crises, leaders will inevitably be confronted with options like punching, kicking, or intiating sustained carpet bombing campaigns. 

Violence inevitably hurts people, and disproportionately affects those who aren't involved in the actual conflict that prompted the violence. 

However, many argue that violence is an answer.

So without further adieu, here is a definitive list of all the times violence was successfully used to resolve systemic issues: 

So that list isn't exactly filled with events. While it is sometimes true that violence becomes necessary to end the psycopathic evil being perpetrated elsewhere (Nazi Germany), violence rarely achieves its intended goal and always creates broad collateral damage. 

In the wise words of Martin Luther King Jr: 

"The ultimate weakness of violence is that it is a descending spiral, 
begetting the very thing it seeks to destroy. 
Instead of diminishing evil, it multiplies it.
Through violence you may murder the liar, 
but you cannot murder the lie, nor establish the truth. 
Through violence you may murder the hater, 
but you do not murder hate. 
In fact, violence merely increases hate. 
So it goes. 
Returning violence for violence multiplies violence, 
adding deeper darkness to a night already devoid of stars. 
Darkness cannot drive out darkness: 
only light can do that. 
Hate cannot drive out hate: only love can do that.

- Martin Luther King, Jr., Where Do We Go from Here: Chaos or Community?, pp. 62-63 (1967)