Russia's Foreign Minister, Izolsky, is desperate to secure access for Russia's Black Sea fleet to the Mediterranean. To do so, he will need to secure access through the Dardanelles, under Turkish control. He meets with his Austro-Hungarian counterpart and they fashion a deal. In return for allowing them to annex Bosnia-Herzegovina, the Austrians will take no action on any Russian moves on the Dardanelles. They also demand that Russia ignore any protests from Serbia, which also has claims on its neighboring territory. Izolsky agrees but incurs the wrath of the Tsar who refuses to abandon Serbia. War is averted, but only just.
—garykmcd