The interwar period in Bulgaria covers the history of the Kingdom of Bulgaria from the armistice of September 1918, which ended the country's participation in World War I, to its entry into World War II in the spring of 1941.

Despite being the most egalitarian society in Eastern Europe in terms of property ownership,Stavrianos, 1958, p. 644. offering significant social mobility, and having no major cultural minorities, Bulgaria experienced chronic violence and the rise of extremist left and right-wing movements during this period.Rothschild, 1990, p. 323. Most of the violence stemmed from the large community of irredentist Bulgaro-Macedonians settled in the country, though anarchists and communists occasionally contributed as well. National politics were turbulent, with numerous parties formed not on ideological differences, but as platforms for their leaders' political careers.Rothschild, 1990, p. 333.

Bulgarian interwar politics can be divided into several phases: an initial period of sweeping reforms under the Bulgarian Agrarian National Union from the end of the war until the coup of 1923, followed by successive governments led by the coup leaders until the onset of the Great Depression. This economic crisis brought a new coalition of reformist parties to power in 1931. They remained in control until another coup was conducted by Zveno, which held power for just one year before the monarch of the period, Boris III, assumed effective control. He retained power until the end of the interwar period and the start of World War II.Stavrianos, 1958, p. 645.

Background The military defeat, partly due to army desertions, war fatigue, and severe hardships on the home front, was formalized in the armistice of September 29, 1918.Jelavich, 1999, p. 167.Rothschild, 1990, p. 326. A few days later, on October 4, King Ferdinand I of Bulgaria, discredited by successive military defeats in the 1913 and 1918, abdicated in favor of his son Boris IIIEvans, 1960, p. 158. and went into exile.Crampton, 2007, p. 218. Despite these political changes, unrest persisted. A military rebellion in Radomir alarmed the government, which quickly released the popular agrarian politician Aleksandar Stamboliyski, who had opposed the war. The Malinov government, which succeeded Vasil Radoslavov in June, was unable to govern or alleviate the dire food situation, surviving only due to fears of a potential Serbian or Greek invasion. Following Romania's occupation of Southern Dobruja, which violated the September armistice, Malinov resigned on November 28, 1918, paving the way for a coalition led by Teodor Teodorov.Evans, 1960, p. 159.

Postwar Period Peace negotiations Following territorial losses from the defeat in the Second Balkan War, the new failure in the world war required Bulgaria to cede Southern Dobruja, the country's "breadbasket", to Romania,Magocsi, 2002, p. 170. certain strategic enclaves to Yugoslavia, and Western Thrace,Crampton, 2007, p. 222. rich in tobacco and Bulgaria's access to the Aegean Sea, to Greece.Jelavich, 1999, p. 166. The country's territory shrank from 111,836 km2 to 103,836 km2. Despite nationalist outrage over the loss of Macedonia, which they considered Bulgarian, the losses of Dobruja and Thrace had a greater economic impact.Rothschild, 1990, p. 325. These territorial losses made Bulgaria a revisionist state, opposed to the political system established by the Paris Peace Conference. The peace treaty also mandated war reparations, payable in currency and livestock, and restricted the size of Bulgaria's army and police forces. The first reparation payment was deferred from 1921 to 1923, but the Sofia government refused to pay,Bell, 1977, p. 205. claiming inability.Crampton, 2009, p. 101. The Allied commission overseeing payments then authorized neighboring countries to occupy Bulgarian customs posts and the Pernik mines, but Yugoslavia's reluctance to act, to avoid straining recently improved relations, led to inaction. Negotiations followed, resulting in a March 1923 agreement that eased Bulgaria's burden: payments were spread over sixty yearsEvans, 1960, p. 162. until 1983, in two phases. The initial payment was reduced from 105 million to just five million, and by the time war reparations were abandoned in 1932, Bulgaria had paid only 70 million francs instead of the agreed-upon 2,250 million.Stavrianos, 1958, p. 655. Even with the new agreement, payments accounted for nearly a quarter of the state's annual budget.

The country's situation The country was exhausted by the war:Evans, 1960, p. 160. cereal production was only 47% of pre-war levels, a third of the national livestock had been lost, nearly 40% of the male population had been conscripted, suffering heavy casualties, and territorial losses brought hundreds of thousands of refugees that the state had to support. Bulgaria had been almost continuously at war since 1912, losing 155,000 combatants (over a fifth of men aged 20–50) and over 400,000 wounded (200,000 disabled), plus 150,000 civilian deaths from epidemics. Bulgaria had mobilized the highest proportion of its male population among belligerent nations.Crampton, 2007, p. 220.

Discontent grew despite the end of fighting.Crampton, 2009, p. 86. Famine was averted only by massive wheat imports, mostly from the United States. However, severe inflation persisted: by 1919, food prices were twelve times higher than in 1914;Crampton, 2007, p. 223. by January 1920, it was twenty-five times higher. Delivering livestock as war reparations to neighboring countries worsened the food crisis and fueled price increases. This hit urban classes hardest, as they relied on wages diminished by inflation. Throughout 1919, public anger grew, culminating in a massive July demonstration in the capital,Crampton, 2009, p. 87. violently suppressed by the socialist interior minister, boosting communists in the August elections. Late that year, socialists and communists, often at odds, united for a general strike,Rothschild, 1990, p. 334.Stavrianos, 1958, p. 646. which failed in early 1920Bell, 1977, p. 151. due to the harsh response from Aleksandar Stamboliyski's agrarian government, which deployed the army, police, and the party's "Orange Guard" against strikers, who were harassed by the cabinet.

The Agrarian Union government In the August 1919 elections, leftist parties secured victory:Crampton, 2007, p. 221. the agrarians won 31% of the vote, communists 18%, and socialists 13%. Stamboliyski became prime minister while participating in peace talks with the war's victors. After failing to persuade communists to form a joint cabinet, he formed a coalition with two small bourgeois parties (those of Ivan Evstratiev Geshov and Stoyan Danev) in October. After crushing the late 1919 general strike, Stamboliyski called elections for March 1920Crampton, 2007, p. 224. to secure an absolute majority. Despite a strong result (110 of 229 seats)Rothschild, 1990, p. 335. and intimidating the opposition,Evans, 1960, p. 161. communists also performed well (51 seats). He invalidated certain deputies' mandates to achieve the majority he lacked.Bell, 1977, p. 152. In May, he formed a new government without coalition partners, relying on a four-seat majority he had engineered in parliament. Stamboliyski then began implementing his reform program, focusing primarily on improving peasant life, often sidelining urban issues.Jelavich, 1999, p. 168. Significant changes occurred during his tenure:Rothschild, 1990, p. 336. a progressive income tax was introduced,Rothschild, 1990, p. 338.Stavrianos, 1958, p. 648.Crampton, 2007, p. 227. an agrarian reformStavrianos, 1958, p. 64.Crampton, 2007, p. 226. and land consolidation were carried out, cooperatives were promoted,Bell, 1977, p. 169.Crampton, 2007, p. 228. and education, especially in rural areas, was improved.Bell, 1977, p. 177. A mandatory labor service was established for public works.Rothschild, 1990, p. 337.Bell, 1977, p. 171. Legal services were made more affordable. The Agrarian Union's pacifist stance and desire for good relations with neighbors led Stamboliyski to reduce the army below the size permitted by the peace treatyCrampton, 2007, p. 231. and place it under civilian control.Bell, 1977, p. 161.

However, Stamboliyski's government had significant weaknesses: he was authoritarian,Stavrianos, 1958, p. 650. his party lacked trained and expert cadres, and many members exploited their control of the government for personal gain, proving themselves to be as corruptCrampton, 2007, p. 230. as their predecessors.Jelavich, 1999, p. 170. His disdain for cities and certain urban classes and professions led to discriminatory or intimidating measures. In September 1922, under the pretext of protecting prominent bourgeois politicians from their own followers,Crampton, 2007, p. 232. they were imprisoned and later accused of involvement in recent wars; they were released only in the summer of 1923 after the coup against Stamboliyski.Rothschild, 1990, p. 340. In the April 1923 elections, the agrarians intimidated the opposition and made arrests to secure victory, achieving 53% of votes against 18.9% for communists. Measures against Macedonian terrorists failed due to the army's lack of interest in dismantling their organizations.Stavrianos, 1958, p. 649.

In international politics, the agrarians sought to comply with the peace treaty while pursuing concessions from the victors.Jelavich, 1999, p. 169. Stamboliyski accepted the cession of Macedonia, believing regional political evolution would lead to a Bulgaro-Yugoslav federation within a larger agrarian confederation, rendering territorial disputes obsolete. This vision, reflected in his support for the Peasant International, led him to reject traditional revisionism and irredentism. His followers promoted the creation of the Agrarian International, which saw little activity, and worked to improve relations with Yugoslavia.Bell, 1977, p. 199.Crampton, 2007, p. 229. Relations with Greece did not improve, as agreement on Thrace proved impossible:Bell, 1977, p. 198. Greece offered tax-free zones in ports, while Bulgaria sought territorial concessions. Despite tensions with Bulgarian communists, Stamboliyski maintained cordial relations with the Soviet Union.Rothschild, 1990, p. 343. He secured Bulgaria's entry into the League of Nations, the first defeated nation to join.Bell, 1977, p. 192.

The final electoral victory in April 1923Bell, 1977, p. 228. emboldened Stamboliyski, who intensified actions against the opposition: in May, he alarmed the monarchy with comments about establishing a republic, antagonized the military by reshuffling commands and turning the Orange Guard into a semi-official force, provoked Macedonians by banning some of their organizations, and targeted communists by arresting some provincial officials.Rothschild, 1990, p. 341.

The coup d'état