 The Treaty of San Stefano was signed on 3 March 1878 by Russia and the Ottoman Empire , and included a provision to set up an autonomous Bulgarian principality roughly on the territories of the Second Bulgarian Empire . The other Great Powers immediately rejected the treaty out of fear that such a large country in the Balkans might threaten their interests . It was superseded by the subsequent Treaty of Berlin , signed on 13 July , provided for a much smaller state comprising Moesia and the region of Sofia , leaving large populations of Bulgarians outside the new country . This played a significant role in forming Bulgaria 's militaristic approach to foreign affairs during the first half of the 20th century . 
