Step-by-step explanation:
In the 19th century, European involvement in the Balkans significantly contributed to the decline of the Ottoman Empire's power in the region. This was primarily achieved through military defeats, nationalist movements, and economic competition. The Russo-Turkish War of 1877-1878 resulted in the loss of significant Ottoman territories, weakening the empire's hold on the Balkans. European powers supported nationalist movements seeking to break away from Ottoman rule, and invested heavily in infrastructure development, providing an alternative to Ottoman-dominated trade routes. These factors ultimately led to the dissolution of the Ottoman Empire and the emergence of several independent Balkan states.