The war started because the Tsar's government supported Serbian regicides. While I do not approve of the deal with Lenin in the least, it has a sort of tragic poetic justice to it.
I didn't realize you were still here. (I'm usually not either.)
I doubt very much that Tsar Nicholas II or his government in 1914 knew about the connections between Gavrilo Princip, the Black Hand, and the Serbian government.
What I don't know is whether Kaiser Wilhelm II personally authorized the deal with Lenin. I get the impression that he was not really in control of much by 1918. Certainly Bl. Emperor Karl was horrified when he learned of the plan. But of course no one on either side was listening to him...