The astonishing thing is that each new weapon, at least before WWI, was thought to be so terrible that it would make war impossible. The machinegun, poison gas and the bomber were all expected to put an end to war. Even the some of the designers of the atomic bomb thought that it would never be used. But given the psychology of leaders like Hitler and Jim Jones (Jonestown massacre) or Sadam Hussein it is inconceivable that a leader who is losing a revolution would not use every weapon in his arsenal. Think back to the US Civil War and imagine what they would have done to prevent the other side from winning. All that is required is a sociopathic leader with access to nuclear weapons. The world abounds with them.
All those weapons should have deterred people from fighting. Were politicians gentlemen, that is. We had no clue how barbarous they could be, even those primed to blame government for everything.