Is War Justifiable???

I read somewhere that War is never justifiable. I must disagree, War is very justifiable. Now war is not always started for a justifiable reason, but by the end there is a justifiable reason, whether it is trying to stop the war or trying to win. Plus without war how would you know peace? We must remember the balance in our world. Some people believe that there should be no wars at all, but for those of you that think that way might want to look in the Bible in Revelation Chapter 12 for it reads in verses 7-9: And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels, And prevailed not; neither was their place found any more in heaven. And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
I know for some, you are going to say "I don't believe in the Bible" and that's fine with me, I'm just using it to show that war has been going on, or talked about going on, for a very long time and I feel that it will continue on for many more years.
Next for those of you who feel that war is never justifiable, would you have liked it better if our founding fathers had decided that they also thought war was not justifiable and had not fought for our independence in the American Revolution. Or should the world have looked the other way and decided to let Adolf Hitler continue his holocaust since war is not justifiable.
Just as there will always be good and bad, there will always be peace and war. And even though war is not something that the world likes to see it is justifiable to keep the peace......