In the late 7th century a branch of the Bulgars led by Khan Asparuh migrated into the northern Balkans, where they merged with the local Slavic population and possibly remnants of the Thracian population to form the first Bulgarian state in AD 681. This was the first Slavic nation-state in history. The Bulgarian empire was a significant European power in the 9th and the 10th century, while fighting with the Byzantine Empire for the control of the Balkans. The Bulgarian state was crushed by an assault by the Rus’ in 969 and completely subdued by a determined Byzantine assault under Basil II in 1018.
It was re-established in 1185 and continued to be an important power in the European south-east for two more centuries by fighting to assert its place in the region with the Byzantine Empire, imposing defeats on the Crusader states in Greece, as well as Hungary. By the end of the 14th century the country was conquered by the Ottoman Empire. A liberation attempt by the Polish-Hungarian forces under the rule of Wladislaus III of Poland was defeated in 1444 in the battle of Varna.
An autonomous Bulgarian principality in its ethnic borders was proclaimed by the Treaty of San Stefano of March 3, 1878, following the Russo-Turkish War, 1877-78. The treaty was immediately rejected by the Great Powers for fear that a large Slavic country on the Balkans would serve Russian interests. This led to the Treaty of Berlin (1878) which provided for an autonomous Bulgarian principality comprising Moesia and the region of Sofia. The first Bulgarian prince was Alexander Batenberg. Most of Thrace was included in the autonomous region of Eastern Rumelia, whereas the rest of Thrace along with the whole of Macedonia was returned under the sovereignty of the Ottomans.
After uniting with Eastern Rumelia in 1885 (followed by a short war with Serbia), the principality was proclaimed a fully independent kingdom in 1908. This happened during the reign of Ferdinand I of Bulgaria. He became Bulgarian prince after Alexander Battenberg abdicated in 1886 following a coup d’etat staged by pro-Russian army officers. (Although the counter coup d’etat coordinated by Stefan Stambolov was successful, Alexander Battenberg could not remain Bulgarian prince without the approval of the Russian emperor Alexander III.) The struggle for liberation of the Bulgarians in the Adrianople Vilayet and Macedonia continued throughout the end of the 19th and the beginning of the 20th century culminating with the Ilinden-Preobrazhenie Uprising organised by the IMARO in 1903.
In 1912 and 1913 Bulgaria became involved in the Balkan Wars, entering into conflict with Greece and Serbia against the Ottoman Empire and then against its former Balkan allies in desperate effort to achieve its national unity. After being defeated in the Second Balkan War, Bulgaria lost most of the territory conquered in the first war, as well as Southern Dobruja. During World War I, Bulgaria found itself fighting on the losing side after its alliance with the Central Powers. The defeat led to new territorial losses (the Western Outlands to Serbia, Western Thrace to Greece and the re-conquered Southern Dobruja to Romania. The Balkan Wars and World War I led to the influx of over 250,000 Bulgarian refugees from Macedonia, Eastern and Western Thrace and Southern Dobruja. These numbers increased in the 1930s following Serbian state-sponsored aggression against its native Bulgarian population.
After regaining control over Southern Dobruja in 1940, Bulgaria allied with the Axis Powers in World War II, although no Bulgarian soldiers participated in the war against the USSR. During this time the country occupied parts of Greece and Yugoslavia. Bulgaria was the only country that saved its entire Jewish population (around 50,000) from the Nazi camps by refusing to comply with a 31 August 1943 resolution. However, Jews in invaded Greek and Yugoslavian territories were sent to death camps by the Bulgarian authorities. In September the Soviet army entered into Bulgaria which enabled later the Bulgarian Communists to seize power and establish a Communist dictatorship. Bulgaria had to fight against Germany (with a 450 000 strong army in 1944 reduced to 130 000 in 1945). More than 30 000 Bulgarian soldiers and officers were killed in the war.
Bulgaria fell within the Soviet sphere of influence after World War II and became a People’s Republic in 1946 and one of the USSR’s staunchest allies. Bulgaria was the most loyal Soviet satellite state during the Cold War. From the late 1970s it began normalising its relations with Greece and from the 1990s with Turkey. The People’s Republic ended in 1989 with many Soviet nations as the Soviet Union itself began to collapse (the Bulgarian Communist dictator Todor Zhivkov was removed from power on 10 November 1989), and Bulgaria again held multiparty elections and privatized its economy, but economic difficulties and a tide of corruption led over 1,500,000 Bulgarians, most of them qualified professionals, to emigrate.
Bulgaria joined NATO on 29 March 2004 and is set to join the European Union at the earliest on 1 January 2007 after signing the Treaty of Accession on 25 April 2005.