The annexation of Bosnia and Herzegovina by Austria-Hungary marked a significant turning point in the political landscape of the Balkans. Although the territories had been occupied by Austria-Hungary since 1878, it was on October 6, 1908, that Austria-Hungary formally declared their annexation, a move that caught international attention. The annexation was primarily driven by Austria-Hungary's intentions to strengthen its position against rising nationalism in the region and the perceived threat from Serbia and Russia, who sought to unite the South Slavic peoples under one nation.The immediate response to the annexation was one of outrage, especially from Serbia, which harbored aspirations of expanding its territory and influence among the Slavic peoples. Russia, being a Slavic nation, was also resistant to the annexation, as it threatened their interests in the Balkans. The Bosnian crisis prompted a series of diplomatic discussions among the Great Powers. It highlighted the fragility of peace in the Balkans and underscored the complex web of alliances and enmities that would play out in the coming decade.The long-term consequences of the annexation were profound. It fueled nationalist sentiments within the region, leading to increased tensions between Austria-Hungary and Serbia. The crisis foreshadowed the conflicts that would explode in the 1910s, culminating in the First World War. The event also led to a redefining of relationships among the European powers, as the backlash from Serbia and Russia laid the groundwork for greater instability and conflict in Europe.