What was the reaction to annexation of bosnia by austria-hungary Eas there an alliance formed due anexation If so what it called?

The annexation of Bosnia and Herzegovina by Austria-Hungary in 1908 was a major diplomatic crisis that increased tensions between Austria-Hungary and Russia, bringing Europe to the brink of war. The Serbian government and much of Serbian public opinion were outraged by the annexation, viewing it as a violation of Serbian national interests and a threat to the country's independence. The annexation also raised fears among other Slavic nations in the Balkans that Austria-Hungary had expansionist ambitions in the region.

In response to the annexation, Russia, which was the main Slavic power in the Balkans and a traditional ally of Serbia, mobilized its army and threatened to go to war with Austria-Hungary. The crisis was eventually defused through diplomatic negotiations, but it left deep divisions and mistrust between Austria-Hungary and Russia.

Formation of the Balkan Alliance

In the wake of the annexation of Bosnia and Herzegovina, Serbia, Bulgaria, Greece, and Montenegro formed the Balkan Alliance in 1912. The alliance was formed in response to the perceived threat from Austria-Hungary and aimed to counter its influence in the Balkans. The Balkan Alliance was a major factor in the outbreak of the Balkan Wars in 1912 and 1913, which resulted in the defeat of the Ottoman Empire and the expansion of the Balkan states.