The Sarajevo crisis was supposed to ignite the world into a four year war that would devastate much of Europe. But what if it didn't? What if, in the dwindling light, when it looked like war was certain, the determination of one man prevented a continent wide conflict.
Bethmann-Hollweg, the German Foreign Minister and an Anglophile, realized that Count Berchtold had double crossed him and was courting disaster. Knowing what he had to do, he recalled Wilhelm from his cruise early, to stop the crisis. After many arguments, he convinced Wilhelm to withdraw the "Blank Check", and declare neutrality in this conflict. Wilhelm agreed, and a proclamation was issued later that day that Germany would not be mobilizing in the defense of Austria.
With Germany staying out, France takes a limited position in the war, and WW1 stays as an isolated war between Austria and Russia, ensuring that the German Reich survives. Austria Hungary falls in a three year war with Russia, fragmenting the Balkans, who slowly polarize around Germany and Russia. The Balkans light the fires of WW1, a war with more advanced tech, and a forknowledge of the impenetrable defense. The world feels the flames of war once again, but this time there is no knowing when they will die out.