[XXi]

However the WWII terrible was, I think the WWI was worse in few aspects.

First, I think that it was the worst war in terms of expectations and preparation of the generals and reality of the battlefield. In WWII, most commanders at least had an idea of the modern battlefield and quite many got to understand it, if not at first then lately. And even if not, blitzkrieg could teach them a lesson or two at relatively low price. In WWI, generals were sending troops into bloodshed with not a slightest idea what was going on and how futile waste of human life it was.