Perhaps think about why would someone engage in conflict in the first place - 'good' or 'evil', what motivates them? What is there to gain? It could be because you feel that something needs to be done or fixed. You could feel that there's some wrongdoing done by the 'other side'. You could be Batman and whatever he wanted to achieve - something which could only be done by confronting the villians that were terrorising Gotham City.
You could suffer losses in a conflict and still come away with positives. The ANZACs landing at Gallipoli in World War I is probably one you've heard - that's considered the embodiment of the Australian spirit or something along the lines of that - something that supposedly strengthened the Australian nation.
You could learn and gain experience and wisdom in the conflicts you face over your lifetime.
Those are just a few ideas to get your mind running, once you have the general ideas you should be able to find the evidence to support quite easily - just look for what fits the situation and what you're actually trying to convey the best.