Should we find a second form of life right here on our doorstep we could be confident that life is a truly cosmic phenomenon. If so there may well be sentient beings somewhere in the galaxy wondering as do we if they are not alone in the universe.
It was quite a European war until 1917 when the Americans joined up. They don't have the same sense of the loss of innocence and the cataclysmic loss of life. A whole generation was wiped out.