Early years and Chervenkov era
After taking power, the Fatherland Front formed a coalition led by former Prime Minister Kimon Georgiev, which included the Social Democrats and the Agrarians. Under the terms of the peace settlement, Bulgaria was allowed to keep Southern Dobruja, but formally renounced all claims to Greek and Yugoslav territory. 150,000 Bulgarians settled during the occupation were expelled from Western Thrace. The Communists deliberately took a minor role in the new government at first, though an all-Communist regency council was set up for the young Tsar Simeon II. The Soviet representatives held the real power. A Communist-controlled People's Militia was set up, which harassed and intimidated non-Communist parties.
On 1 February 1945, Regent Prince Kiril, former Prime Minister Bogdan Filov, and hundreds of other officials of the kingdom were arrested on charges of war crimes. By June, Kirill and the other Regents, twenty-two former ministers, and many others had been executed. The new government began to arrest Nazi collaborators. Thousands of people were charged with treason or participating in counter-revolutionary conspiracy and sentenced to either death or life in prison. When the army returned following the German surrender, the regime also purged the officer corps. As the war came to a halt, the government expanded its campaign of political revolution to attack economic elites in banking and private business. It is estimated that, between 1944 and 1989, between 5,000 and 10,000 people were killed in Bulgaria as part of agricultural collectivisation and political repression, although documentation is insufficient for a definitive judgement. Figures for fatalities in forced labour camps also remain elusive. According to official sources, 2,730 people have been sentenced to death, but unofficial estimates suggested that as many as 20,000 people were reported killed under the regime between 1944 and 1989.
These revolutionary attacks strengthened when it became apparent that the United States and United Kingdom had little interest in Bulgaria. In November 1945, Communist Party leader Georgi Dimitrov returned to Bulgaria after 22 years in exile. He made a truculent speech that rejected cooperation with opposition groups. Elections held a few weeks later resulted in a large majority for the Fatherland Front.
In September 1946, the monarchy was abolished by plebiscite, which resulted in 95.6 percent voting in favour of a republic, and Simeon was sent into exile. The Communists openly took power, and Bulgaria was declared a People's Republic. Vasil Kolarov, the number-three man in the party, became president. Over the next year, the Communists consolidated their hold on power. Elections for a constituent assembly in October 1946 gave the Communists a majority. A month later, Dimitrov became prime minister.
The Agrarians refused to co-operate with the authorities, and in June 1947 their leader Nikola Petkov was arrested, despite strong international protests. The new Agrarian leader, Georgi Traykov, repudiated his party's traditional ideology and defined a new role for it as the helpmate of the Bulgarian Communist Party. This marked the formation of a Communist establishment in Bulgaria. In December 1947, the constituent assembly ratified a new constitution for the republic, referred to as the "Dimitrov Constitution". The constitution was drafted with the help of Soviet jurists using the 1936 Soviet Constitution as a model. By 1948, the remaining opposition parties were either realigned or dissolved; the Social Democrats merged with the Communists, while the Agrarian Union became a loyal partner of the Communists.
During 1948–1949, Orthodox, Muslim, Protestant and Roman Catholic religious organisations were restrained or banned. Both Protestant and Catholic preachers were frequently accused by Communist prosecutors of having ties to Western intelligence agencies, particularly those of the United States and United Kingdom. The Orthodox Church of Bulgaria continued functioning but never regained the influence it held under the monarchy; many high roles within the church were assumed by communist functionaries.
Dimitrov died in 1949 and for a time Bulgaria adopted collective leadership. Vulko Chervenkov led the Communist Party and Vasil Kolarov was prime minister. This broke down a year later, when Kolarov died and Chervenkov added prime minister to his titles. Chervenkov started a process of rapid industrialization modeled after the Soviet industrialisation led by Stalin in the 1930s and agriculture was collectivised.
Stalin's death in 1953 had political repercussions in Bulgaria. In 1954, Chervenkov accepted the collective leadership, remained prime minister, but ceded his position as party leader to Todor Zhivkov. The government also released a large number of political prisoners and focused on improving living standards rather than accelerating industrialization. Chervenkov stayed on as prime minister until April 1956, when he was finally dismissed and replaced by Anton Yugov. With the official start of de-Stalinization in 1955, censorship was relaxed somewhat and the victims of the Kostovite trials, including Kostov himself, began to be rehabilitated.
By the mid-1950s, living standards rose significantly, and in 1957 collective farm workers benefited from the first agricultural pension and welfare system in Eastern Europe. Bulgaria underwent rapid industrial development from the 1950s onwards. Starting with the 1960s, the country's economy appeared profoundly transformed. Despite the achievements of this modernisation, many difficulties remained, such as poor housing and inadequate urban infrastructure.
