Bulgaria had been part of the Ottoman Empire since 1396. In the late nineteenth century, a growing tide of nationalism had been spreading across Europe, which had been threatening the break up of the western parts of the Ottoman Empire.
In April 1876, uprisings in other parts of the Ottoman Empire spread to Bulgaria. The suppression of the revolts by the Ottomans was horrific and when the atrocities were made public to the West and Russia, international condemnation was widespread. In 1877, Russia formally declared war on the Ottoman Empire. The conflict eventually resulted in the creation of a Bulgarian principality within the Ottoman Empire, albeit with reduced land.
Following a war with Serbia, the principality extended its area in the region and on September 22nd 1908, in the Veliko Tarnovo, a manifesto, Prince Ferdinand of Bulgaria declared Bulgaria’s independence from the Ottoman Empire and Bulgaria reappeared on the map of Europe after five centuries of Ottoman rule.
In 1908, Bulgaria was still using the Julian calendar, so the declaration of independence was made on October 5th using that calendar.