The “war to end all wars” was a family affair, with Charlemagne, “Father of Europe”, the “Uncle of Europe”, and even Kaiser Wilhelm II saying grandma Queen Victoria would have stopped it. 
Germany planned for a 40-day victory; four years later, 9-22 million lay dead and more were wounded. The war plans failed. Germany was encircled. The trenches were a bloody reality. 
The modern world was forged in an almost-forgotten nightmare-war of killing technology.