WWI was based on the existence of an alliance system that meant Germany had to attack France to go to war with Russia when it wanted to go to war with Russia, the alliances themselves existing because the German Empire was too damn big and too damn strong. Germany's requirement to invade in the West guaranteed a big war, and that's a lot more clear than butchering hundreds of thousands of people over what might be the case distant decades in the future, which is what Lee, Pemberton, Kirby Smith, and Braxton Bragg did.