"Amy Pond. Get. Your. Coat."

Demons run when a good man goes to war
Night will fall and drown the sun
When a good man goes to war
Friendship dies and true love lies
Night will fall and the dark will rise
When a good man goes to war
Demon’s Run, but count the cost
The battle’s won but the child is lost

Nothing good happens when a good man goes to war

But I also like the saying "If you want peace prepare for war". War is not the right choice, but it's seldom yours.

I once played D&D with a paladin who basically followed this. He was an Oath of Vengeance paladin. For the unaware, OoV paladins often have zero chill. They’re typically something akin to Batman with magic powers. My goal was to avoid that.

His oath had something along the lines of “Without the capacity for violence, pacifism is not a choice. Pacifism without choice is victimhood. I will choose pacifism whenever possible, but will not watch idly when people are victimized. I will ensure the victimized are made whole, and the victimizers know the pain they have caused.”

Basically, he would try his best to talk his way through encounters first. He would give enemies every opportunity to back down. He had incredibly high charisma to try and persuade, intimidate, or deceive others out of attacking. After all, he was attempting to choose pacifism whenever possible. But if he believed that a bully was victimizing someone, the gloves came off and he channeled all of his pent-up fury into making the bully regret their actions. And since paladins use charisma to cast their spells, his smites were painful.

The DM loved it, because it helped us avoid falling into the murderhobo trope that combat-oriented D&D players often fall into. It also gave him a chance to actually flesh out some of the NPCs who would have just been throwaway no-name combatants.

Yeah, although the Doctor is pretty hypocritical with his pacifism. Something which this quote sums up pretty well. He did kill several species after all.

Demons worry when the wizard walks by.