Plovdiv, Bulgaria's second largest city, is in the focus of the festivities in the country as it celebrates the 126th anniversary since its unification.

A solemn retreat starting 20:30 local time on Tuesday will be the culmination of the celebrations in the city, the bTV private channel has informed. The holiday is also marked with events all across the country.

Bulgaria's President Georgi Parvanov and Parliamentary Speaker Tsetska Tsacheva are present at the event.

On September 6, 1885, the Principality of Bulgaria unified with the autonomous Ottoman province of Eastern Roumelia, a few years after its liberation from Ottoman yoke.

The historic proclamation was made after a march by a handful of Bulgarians from the small town of Saedinenie  ("Unification") to the town of Plovdiv, removing one of the gravest injustices imposed in the wake of the Berlin Congress. The Unification was prepared by a network of secret revolutionary committees in Eastern Roumelia, and was backed by the then Bulgarian ruler, Knyaz (King) Alexander I Batenberg.

Great Britain had been the primary protagonist in downsizing Bulgaria during the Berlin Congress because it feared a large Bulgarian state with access to the Mediterranean would be under Russian influence. However, in 1885-1886, it backed informally but rather noticeably, Bulgaria's Unification, seeing that the Russian Empire at the time was against this move, which stirred diplomatic tension in the Balkans, and seized the chance to demolish Russian influence in Bulgaria.

As other Balkan countries objected to Bulgaria's Unification, Serbia attacked Bulgaria in November 1885. In a grand national effort to defend the Unification, the young Bulgarian Army, which had just been left by its senior Russian officers, repulsed the attack, and defeated the Serbs on their territory, thus making the Unification of Northern and Southern Bulgaria a fait accompli.

But it was not until 1886 when the Great Powers recognized the almost doubled state of Bulgaria with a Bulgarian-Ottoman treaty.

After the Unification of 1885, Bulgarian efforts were focused on making Macedonia and the rest of Thrace part of the country. Thus, Bulgaria backed the VMORO (Internal Macedonian-Adrianople Revolutionary Organization) and its staging of the failed Ilinden-Preobrazhenia Uprising in 1903, and subsequently took part in the Balkan Wars of 1912-1913, World War I (1915-1918) and World War II (1941-1945).