There was plenty of gung-ho warmongering all around. Austria declared war on Serbia, yes, but that didn't automatically involve Russia, Germany, France, Britain, Italy, the Ottoman Empire, Japan, or the United States. Each nation was responsible for its own behavior, and as best I can see they all went whacko. Germany must bear her share of the blame, but so must France, Britain, and Russia. As for German mobilization, this was done in anticipation of a French declaration of war, which the French duly provided. There are a number of unpleasant things one can say about German behavior during the war, such as violation of Belgian neutrality and the execution of innocent hostages after sabotage or guerrilla attacks, but it's going too far to accuse any one nation of "starting the war."

A good book on the subject is Barbara Tuchman's The Guns of August. The description of French attitudes alone is revealing. The French were thirsting for revenge for 1870. A common graffitum in Paris was "Quarante-Huitante" ("Forty-Eighty"), with the implication that as there were 40 million Frenchmen and eighty million Germans, if every Frenchman killed two Germans Germany would be annihilated.