This might be an obvious question, but after watching this video, visualizing the loss of life in the war, I was curious as to how citizens found in themselves the sense of civic duty^1 to stand by their nations in the face of such horrific violence; how were there not massive revolts?
For Germany, they believed the war was necessary. As the boys were fighting in the same places their parents and relatives were fighting decades before. They saw the war as something that was inevitable, and many geared up in the hopes their kids wouldn't have to fight savagely like they were then. They largely kept that mentality throughout the war.
I got that info from the book "The German War"