The Kaiser gave free reign to the Austrians by letting them know that he would back them. If such assurance had not been forthcoming then the war may have been avoided.
In the exact same manner that the russians gave free reign to Serbia, by letting them know that they would back them.
Tsar Nicholas who was a weak willed man and had no heart for war tried to avoid it. A study of the correspondence between the Kaiser and the Tsar shows Nicholas tried to get the Kaiser to back down which he refused to do.
The correspondence shows nothing. Both parties are equally "polite" in their telegrams. They both tried to avoid war (in the first two or three telegrams), but were never willing (none of them) to back down from their original stance: The Tsar wanted the Kaiser to put pressure on the Austrians to stop their agression. The Kaiser wanted the Tsar to allow Austria-Hungary to deal with the responsible parties for the assasination on their own, without letting the situation escalate into a greater war. Neither were willing to back down from their stance. When Austria didn`t back down from their confrontation with Serbia (!!!), Russia mobilised.
Tsar Nicholas who was a weak willed man and had no heart for war tried to avoid it.
The russians mobilised first, shortly after the Austria-Hungarian declaration of war on Serbia july 28, 1914. In the military and strategic thinking of that time (early mobilisation gave the upper hand), this was the same as a declaration of war. Hence followed the declaration of war by Germany against Russia on August 1, 1914. And there goes the whole ball game...
Who fired the first shot? The Serbians, the "little brothers" of the russians. We can of course argue whether or not the Serbian assasination was part of a rightful will to independence for Serbia, but this becomes meaningless, as we are discussing the reasons for, and responsibility for WW1. Who mobilised first? Russia. The close bonds and treaties between Serbia and Russia were no different than the bonds between Austria-Hungary and Germany.
In all fairness: Everyone will understand that the Russians could never retract their support to the Serbians. Just like Germany could never retract their support to the Austrians. The bonds were unbreakable, on both sides. The war could not have been avoided (on either side), at least not without one party "losing face"...and in that era, for a "gentleman", "losing face" was out of the question.
Like I said: An accident. No modern, unbiased historians are willing to place the responsibility of that war on the Kaiser anymore. The tradition of putting the responsibility on Germany, was a very biased, anti-german tendency, a tradition that has continued thruout the 20th century. Germany lost the war, and therefore, the responsibility was put on them. That caused a lot of problems for Germany, and the germans were (righfully) outraged over the fact that the responsibility was put on them. This, in part, contributed to the rise of National Socialism. And so forth...