Bulgaria's entry into the Central Powers marked a significant shift in World War I's Balkan theater. Following the Balkan Wars (1912-1913), Bulgaria sought to reclaim territories that had been lost, particularly aiming to annex parts of Macedonia and Thrace. Viewing the Central Powers as potential allies in achieving these aims, the Bulgarian government, led by Prime Minister Vasil Radoslavov, made the pivotal decision to align with Germany, Austria-Hungary, and the Ottoman Empire. This strategic partnership expressed Bulgaria’s national ambitions and its dissatisfaction with previous treaties that left much of its territorial hopes unfulfilled.The formal alliance was established after considerable negotiations and a demonstration of military support from the Central Powers. Bulgaria was motivated not only by the desire for territorial expansion but also by its fierce animosity towards Serbia, which had emerged stronger after the Balkan Wars. On October 14, 1915, Bulgaria signed a treaty, essentially formalizing its commitment to the Central Powers and facilitating joint military operations against Serbia. This alignment effectively opened a new front in the war, allowing the Central Powers to exert pressure on Serbia and gain control of critical strategic regions.The repercussions of Bulgaria's decision were felt throughout the war, as it contributed to the Central Powers' efforts in the Balkans. Bulgarian forces played a significant role in the occupation of Serbia and participated in various battles that would shape the course of the war. The alliance not only reshaped military strategies but also adjusted political alliances and enmities in Southeastern Europe, leading to complex interactions between neighboring countries.