Austria dragged Germany into it.
The Kaiser really didn’t want it, but he had too many of his generals itching for a fight with Russia, because it was a case of “Now Or Never”, with Russia quickly modernizing.
On July 31st, the same day that Cossack patrols had been spotted crossing the German border (presumably for reconnaissance purposes), Wilhelm II telephoned the Czar and pleaded with him to stop the Russian mobilization, which had begun the day before.
The Czar replied that he couldn’t do that anymore (maybe, without him knowing, his cabinet had ordained the mobilization) and he was praying for his cousin. Then he hung up.
I forget who the historian was who said that Europe was complacent because it had actually been able to resolve earlier crises without world war.
There’s a docudrama film called 37 Days. The most striking moment for me was when the kings, politicians, and diplomats are still arguing things and the German Army is at that moment going into Luxembourg.