Bulgaria during World War II in the context of "Vardar Macedonia"

After the Russo-Turkish War of 1877–1878, the 1878 Treaty of Berlin set up an autonomous state, the Principality of Bulgaria, within the Ottoman Empire. Although remaining under Ottoman sovereignty, it functioned independently, taking Alexander of Battenberg as its first prince in 1879. In 1885 Alexander took control of the still-Ottoman Eastern Rumelia, officially under a personal union. Following Prince Alexander's abdication (1886), a Bulgarian Assembly elected Ferdinand I as prince in 1887. Full independence from Ottoman control was declared in 1908.

In the 1912–1913 Balkan Wars, Bulgaria initially formed an alliance with Greece, Serbia and Montenegro against the Ottoman Empire, and together they conquered a great deal of Ottoman territory. Bulgaria, however, unhappy with the resulting division of territory, soon went to war against its former allies Serbia and Greece and lost territory it had gained in the first war. The First World War (1914–1918) saw Bulgaria fighting (1915–1918) alongside Germany, Austria-Hungary, and the Ottoman Empire. Defeat led to the Treaty of Neuilly-sur-Seine (27 November 1919), in accordance with which Bulgaria lost further territory. Social problems and political instability persisted throughout the Interwar period. In the Second World War (1939–1945), Bulgaria again allied with Germany (March 1941). Although Sofia attempted to pull out of the war as the Soviet Union advanced towards its territory (1944), the Red Army invaded (September 1944), and a communist government came to power (1944–1946) and established the People's Republic of Bulgaria (1946–1990).

Dragiša Cvetković (Serbian Cyrillic: Драгиша Цветковић; 15 January 1893 – 18 February 1969) was a Yugoslav politician active in the Kingdom of Yugoslavia. He served as the Prime Minister of the Kingdom of Yugoslavia from 1939 to 1941. He developed the federalization of Yugoslavia through the creation of the Banovina of Croatia via the Cvetković–Maček Agreement with Croat leader Vladko Maček. He signed the Yugoslav accession to the Tripartite Pact on 25 March 1941. Two days later, on 27 March, a group of officers carried out a military coup, and arrested Dragiša Cvetković and other ministers. German authorities arrested him on two occasions and took him to Banjica concentration camp. He fled on 4 September 1944 for Bulgaria. He spent the rest of his life in Paris.

He previously served as mayor of Niš. On 25 September 2009, the regional court in Cvetković's hometown of Niš rehabilitated him from charges laid against him by the Yugoslav government in 1945.

The Fatherland Front (Bulgarian: Отечествен фронт, ОФ, romanized: Otechestven front, OF) was a Bulgarian pro-communist political resistance movement, which began in 1942 during World War II. The Zveno movement, the communist Bulgarian Workers Party, a wing of the Bulgarian Agrarian National Union and the Bulgarian Social Democratic Workers Party all became part of the OF. The constituent groups of the OF had widely contrasting ideologies and had united only in the face of the pro-German militarist dictatorship in Bulgaria. At the beginning, the members of the OF worked together, without a single dominating group. Professional associations and unions could be members of the front and maintain their organisational independence. However, the Bulgarian Communist Party soon began to dominate. In 1944, after the Soviet Union had declared war on Bulgaria, the OF carried out a coup d'état (9 September 1944) and declared war on Germany and the other Axis powers. The OF government, headed by Kimon Georgiev of Zveno, signed a ceasefire treaty with the Soviet Union (28 October 1944). In the summer of 1945 most of BANU led by Nikola Petkov and most of the Social-Democrats had left the OF and became a large opposition group which later on after the 1946 Grand National Assembly election would become a coalition named "Federation of the village and urban labour" with 99 MPs out of 465.

On November 18, 1945, the OF won a large majority in national elections. In November 1946 Georgiev resigned as Prime Minister and was succeeded by Georgi Dimitrov, leader of the communists. Bulgaria became a People's Republic on 15 September 1946 after a referendum. In 1948 and 1949 all the remaining parties in the OF save for the pro-communist wing of the BANU self-dissolved and merged into the BCP. The OF eventually transformed into a wide-ranging popular front under overall Communist control.