Answer: Kaiser William's support of Austria Hungary to declare the war on Serbia.
Explanation: At the time of strengthening national consciousness and national awakening on the one hand, and investing in the army, weapons storage and making alliances, on the other hand, Europe was approaching the WWI. It was known who would support whom in the case of an attack, so in such an atmosphere Kaiser William, believing in his German supremacy, supported Austria Hungary to announce the war to Serbia.
