It was Germany that pushed Austria to make war on Serbia. It was Germany that declared war on Russia, on August 1 1914. It was Germany that decided it was necessary to invade Luxembourg, and it was Germany that deployed the Schlieffen plan (devised in 1905, incidentally) and sent her troops smashing through neutral Belgium and into France. The statement, which I think is the extent of the particulars supporting the claim of Germany's war guilt, is full of historical inaccuracies. Germany did not push Austria to make war on Serbia. Germany only declared war on Russia after Russia mobilized and declined to demobilize, mobilization in those days being terribly threatening because of the state of technology closely associated with railroad timetables etc.. The invasion of Luxembourg hardly caused World War I, it was an event in the war after it commenced. The von Schlieffen plan was a war plan, just like the war plans maintained today in our Pentagon and in the staff offices of virtually every army in the world. So what?
This argument about responsibility for the start of World War I has now been going on for century and will continue no doubt with more bad historical analysis.
Germany indeed did push Austria-Hungary toward war. A-H would never have undertaken an invasion of Serbia under threat of Russian counterattack without German backing. Germany essentially gave A-H approval for the invasion of Serbia by promising to declare war on Russia if she should mobilize to oppose the Serbian invasion. Until that time, the alliance between Germany, Austria-Hungary and Italy was a defensive one - all promised to support any others who were attacked by an outside power. That’s why Italy ended up on the Allied side; they declined to hold to the alliance because A-H was the aggressor, not the nation attacked. Germany could have done the same and remained neutral during the Austrian/Serbian conflict. Had they done so, it’s likely A-H would never have invaded and risked war with Russia.
In the actual event, Russia mobilized to oppose the Austrian invasion of Serbia. Germany saw this as a threat because its war plans called for defeating France on the western front before Russia had time to fully mobilize. Germany had to declare war against France and Russia so that they could defeat France before Russia completed its mobilization. Thus, the Schlieffen plan did cause Germany to pursue aggression against a neighbor that had nothing to do with the immediate crisis.
The truth is that Germany intentionally inserted itself into a diplomatic crisis that really did not involve Germany. They encouraged A-H to take a hard line with Serbia by promising support in the form of a war declaration should Russia threaten to oppose the invasion. When Russia mobilized, they declared war on Russia as promised, and then involved France and England by virtue of implementation of the Schlieffen plan. How does Germany not receive the bulk of the war guilt given all this? Had Germany not intervened, the assassination of Franz Ferdinand would have been a limited Balkan crisis. Certianly crises in the Balkans were fairly common at the time, but only one of them led to a war involving all the major powers.
I’m sure that had the Germans known what they were about to unleash, they would have backed off. However, WWI was really the first modern war fought by industrialized great powers. Warfare up to that time was not really too damaging to the belligerants. Nobody expected a protracted war, and nobody expected so much death and destruction. War was seen as an acceptable tool of statecraft at that time. Germany did intentionally seek out a war; they almost certainly did not intentionally seek the disaster that actually occurred.