Britain’s “alliances” with France and Russia started out as a way of resolving colonial disputes in Africa and Asia. It was an “entente” or understanding. Those difficulties resolved, Britain should have developed a similar entente with Germany. That didn’t happen. Britain doubled down and sank deeper into its alliances with France and Germany, and Germany was riding high and not very likely to be responsive to overtures that the British could have made.
Getting more into the details, a Serbian agent assassinated an Austrian Archduke and heir to the Austrian throne. Austria addressed an ultimatum to Serbia that would have crippled Serbia in different ways. My understanding is that the Serbs accepted most of ultimate, but rejected some of the more extreme items. This gave Austria an excuse to go to war with Serbia. Germany gave Austria a blank check that allowed and encouraged the Austrians to go to war.
As it was, the Austrians on their own couldn’t conquer Serbia. The harvests were coming and Austrian soldiers didn’t want to leave their farms. Austria was much weaker than it looked. Bearing that in mind, the Austrians should have accepted Serbia’s response to the ultimatum and used the influence in Serbian affairs that it gave them to uproot the conspiracy and either weaken Serbia or manipulate Serbia into friendlier ways. The Germans should have pressured Austria to accept the Serbian response. Russia and France should have recognized that the Serbs would have to pay a cost for the assassination and been more conciliatory with Austria. Then there would have been no war.
The problem is that German and Russian generals wanted war, and their governments weren’t going to stop them.
Well, there wouldn’t have been WW1 as we know it, at least. I’m still pretty sure that there would have been some sort of a war or wars, albeit with a different cast of characters and possibly restrained to just Europe.
The Kaiser’s Blank Check promise to the Austro-Hungarians and Germany’s insistence on attempting to become a top tier Great Power by challenging the British which is what led to the Blank Check in order to get the Austro-Hungarians on side is the final measure that escalated the stupid Serbian dispute into the monster known as World War 1. If the Kaiser hadn’t honored his Blank Check promise or had simply had a more normal defensive treaty, the whole thing falls apart. The Kaiser’s backing is what made the Austrians not accept Serbia’s proposition.
The “blank check” that Wilhelm gave to A-H was done in the belief that the Russians wouldn’t fight, because he didn’t feel the Russians at that point were strong enough. He freaked out when he actually saw Nicky mobilizing, and that’s why he sent him the letter pleading for him to stop it.
Another thing that the history books won’t tell you:
In 1914 after hearing of Serbia’s response to the Austro-Hungarian empire’s ultimatum Kaiser Wilhelm said this “A great moral victory for Vienna but with it, all reason for war is lost”.
So he didn’t see any reason for A-H to go to war with Serbia at that point.