Disagree on Austria-Hungary. Serbia gave Austria-Hungary everything they demanded, but it wasn’t enough for them, they wanted war.
What did Serbia give Austria-Hungary?
What did Serbia give Austria-Hungary?
To wit: the Black Hand was a Brown Shirts-like organization directly funded by Serbia, and organized by Serbian militia, and promoted heavily by Serbian media.
Serbia replied that it would turn over anyone for which proof existed that they conspired against the Archduke Ferdinand, but claimed that there was no such proof, that any anti-Austrian-Hungarian propaganda was the free speech of private individuals and could not be legally suppressed (even when it came openly from the Serbian military).
Serbia also said it was willing to stop propagandizing against Austria-Hungary in its schools, but only after any specific incident was somehow witnessed and proven; Serbia didn’t even make any promises to direct any teachers or school officials not to propagandize.
Serbia promised to remove from the military anyone fomenting violence against A-H if any proof could be found.
Even if A-H provided actual proof of propaganda, Serbia literally promised to explain away what was meant, making it quite clear that Serbia would not prosecute, suppress or correct propaganda even when it was proven to come directly from official, Serbian sources.
Wrong.
The British forced the Serbs to reject the Ultimatum, written by Austria-Hungary. The British started WWI, forced it in fact.
Serbia was not willing to admit to their responsibility in the assassination - and they were responsible. They funded the terrorist group, fomented its actions and even provided the very pistol that was used to carry out the murders.
The Hapsburgs knew it.