Final answer:
Between 1856 and 1878, the Balkans were a major point of contention among Great Powers due to the weakening Ottoman Empire, Austria-Hungary's territorial ambitions, Serbia's unification efforts, and Russia's pan-Slavic interests, setting the stage for future conflicts.
Step-by-step explanation:
The period between 1856 and 1878 in the Balkans was one of tension and political intrigue among the Great Powers. The declining Ottoman Empire was losing its grip on the region, which contained a myriad of ethnic groups and religions, creating a vacuum that other powers sought to fill. Serbia, after gaining independence in 1878, had ambitions of unifying the Balkans under Serbian leadership, which was greatly opposed by Austria-Hungary, who had their own territorial designs on the area. Additionally, the concept of pan-Slavic nationalism gained traction, with Russia showing special interest as a protector of Slavic peoples and as a rival to both Austria-Hungary and the Ottomans. This set the stage for future conflicts that would eventually escalate into the First World War.