Kingdom of Bulgaria

The period from 5 October 1908 to 15 September 1946 is known as the Kingdom of Bulgaria. It is marked by the declaration of Bulgarian independence on 22 September 1908. This was a major step in the development of Bulgarian statehood, accompanied by the monarch's change of title from prince to tsar and the country's official change of name from the Principality of Bulgaria to the Kingdom of Bulgaria.

The kingdom lasted until 15 September 1946, when the People's Republic of Bulgaria was proclaimed following a referendum in which a large majority of voters supported a change in the form of government.

The First Balkan League and the Balkan War of 1912–1913 were important stages in Balkan and Bulgarian history. They resulted from serious efforts to create an anti-Ottoman coalition dating back to the 1860s, which had encountered various obstacles.

Differences between Bulgaria, Serbia and Greece over the Macedonian question intensified in the early twentieth century. Each country's desire for territorial expansion and control in Macedonia generated tension and conflict. Russia supported efforts to form an anti-Ottoman coalition, seeking influence in the region and wishing to prevent Austria-Hungary's expansion into the Balkans.

On 29 February 1912, Bulgaria and Serbia concluded a military alliance directed against Austria-Hungary, Romania and the Ottoman Empire. This developed within the First Balkan League, which also included Greece and Montenegro. The allies allocated among themselves the territorial gains expected from the forthcoming war against the Ottoman Empire.

In August 1912, Bulgaria, Greece and Serbia concluded alliance treaties supported by British mediation. These were accompanied by intensive negotiations over control of Macedonia and other disputed territories.

The ensuing Balkan War brought major successes for the Balkan allies and brought the Ottoman Empire to its knees. Unresolved questions, however, including the division of Macedonia and the size of war reparations, caused a rift among the Balkan states and led to later conflicts.