"As Long as There Are Two People Left on the Earth, Somebody is Gonna Want Somebody Dead"

War is, simply put, two sides fighting for what they want to achieve. Whether we think of Hitler's planting of Nazi flags over the greater half of Europe or Bush ordering a chorus of $300,000 missiles into a cave full of Muslim extremists in the Middle East, war is war. The question is, of the many wars fought throughout this centuries of human history, was every one needed?

Where would each of the sides have been if they hadn't been pumping resources into killing each other? If that money had been spent on their own country, what advancements would we have and what problems would we solve by loading soup kitchens with food instead of Chinooks with armed troops? Who would have been alive if they weren't sent to die for their country, and what would he/she have done with his life if it didn't end fighting in a war? These are all questions we can ask, but never answer.
War is a way of life and has been as long as the pen and paper can stretch back. We were throwing sticks and rocks and arrows at each other when all we had were sticks and rocks and arrows, and now we're throwing bombs the size of a Volkswagon into caves because two countries disagree. Wars have stretched over the world and consumed the innocent and young alike, the Earth under bustling cities lacerated by the things we throw and launch and shoot at people we don't like.
Still, we have to remember that not all wars are as simple as "I don't like you and you don't like me". Genocidal fiends rise to power, as not every government is as benevolent and fair as ours. All these evils and unfairnesses in mind, we can't just label war as killing and thus assume it can be done without as killing can be done without. People die and new ones replace them, reigns end, and conflicts smooth over as a war progresses. Does that mean every military victory is a step closer to world peace? No. However, we have to appreciate the value of force in some scenarios. Unless you plan on personally reasoning with the people we're sending helicopters full of troops to pacify, it would be best for you, as a constituent of the country the warmongers keep secure, to not devalue the necessity of war. Remember, if we didn't enter a war 50 years ago, "Nazi" might still be a household word, and if we didn't start one 250 years ago, we'd probably still be British.