European nations formed opposing alliances to protect themselves from their enemies. And the alliances made them stronger, both militarily and economically.
Because of its constant disagreements regarding land distribution and an extreme sense of nationalism. Also a lot of wars took place there or because of that place such as WWI, WWII, and WWIII.
They took it very seriously. They invaded Serbia with thousands of troops. It was not just considered a murder but an attack on the empire itself.
Geography gave the central powers a disadvantage, as they were surrounded by their enemies. ... If civilians were unhappy, they might not work well or they might create domestic unrest that would unset war plans and demoralize soldiers.