With the volatile and politically unstable atmosphere of Central Europe in the inter-war years, the establishment of independent governments of the former Austro-Hungarian Empire in November 1918 would see the struggle to regain territories of the former empire. However, the Hungarian President of the Hungarian Democratic Republic, Mihály Károlyi, resigned within four months in favor of Béla Kun, a pro-Bolshevik who had been sent by Lenin, quickly seizing power and establishing a revolutionary government.
Military conflicts
During the war, the Hungarian red army fought separate battles against troops from Czechoslovakia and Romania, while France was also highly involved diplomatically in the conflicts, too. By its final stage, more than 120,000 troops on both sides were involved. Appealing to Hungarians with promises of regaining the land lost until then to neighboring countries within a week of his rise to power, Kun declared war upon Czechoslovakia as Hungarian forces invaded Upper Hungary on May 20, capturing southern territories within weeks. In the face of advancing Hungarian troops, the Allies began to put pressure on the Hungarian government and, within three weeks with Kun's assurances of Russian support failing to materialize, Hungary was forced to withdraw from the just proclaimed Slovak Soviet Republic after given an ultimatum from France together with a guarantee that Romanian forces would retreat from Tiszántúl. The Romanians disregarded the guarantees of the French leadership and remained on the eastern banks of the Tisza river. The Hungarian government claiming to impose the will of the Allies on Romania, and seeing that diplomatic solutions would not compel them, resolved to clear the threat by military force once and for all. They planned to throw the Romanians out of Tiszántúl, destroy the Romanian army and even retake Transylvania. However, the Hungarian offensive was defeated by the Romanian army, and despite all previous pledges, agreements and guarantees, the Romanians crossed the river Tisza and quickly advanced towards Budapest. The Hungarian capital fell on August 4, only three days before Kun's escape to Vienna. The destruction of the Hungarian Soviet Republic and the Romanian occupation of parts of Hungary proper, including its capital Budapest in August 1919, ended the war. Romanian troops withdrew from Hungary in March 1920, after seizing large amounts of goods from Hungary, which they regarded as war reparations.
Consequences
Due to the Hungarian-Romanian war the country was totally defeated. In the name of what they considered to be war reparations, the Romanians claimed the delivery of 50% of the country's rolling stock, 30% of its livestock, twenty thousands carloads of fodder and even assessed payment for their expenditures. By the beginning of 1920, they had seized much from Hungary, including food, trucks, locomotives and railroad cars, factory equipment, even the telephones and typewriters from the government office. The Hungarians regarded the Romanian seizures as looting. The Romanian occupation lasted for nearly six months. After the Romanian occupation, Horthy's "White Terror" was carried out in response to the previous "Red Terror". The Hungarians had to cede all war materials, excepting those weapons necessary for the troops under Horthy's command.
