The horse has a rider, one who directs it. The answer is that Christ does. No, war does not run haphazardly through history, without divine direction. War is also under the sovereign control of Christ who causes all things to work together for good to them that love God, Rom. In directing war in this manner, Christ does not force men to fight against their will.
War finds expression in the depraved nature of man.
We need but remind ourselves that sin makes man greedy, he covets what his neighbor has. In trying to satisfy this lust for power and wealth, man will resort to murder, to open conflict. There is something else that we must add to this. Not only did man fall into sin as an individual, he fell into sin as a king. Adam was the king of creation.