I think you're right that anyone aware of the horror of war hates war, but many are swept up by jingoisitc fervor and support things they don't understand.
I must, however, ask how it can be that countries will back off when they see another's might, when that basically hasn't really happened in the past? War has declined in frequency in recent decades not because the powerful assert their might and put fear into other powers, but because the majority of wars have been the powerful teaming up against the weak, using insecure countries as battlegrounds for greater political and economic conflicts. As our economy becomes more and more intertwined globally, and as capital becomes concenctrated in a global elite, war will be seen for what it is by the empowered classes: illusory, unprofitable, and devastating.