[3] The Hungarian Soviet Republic was a small communist rump state[4] which, at its time of establishment, controlled approximately only 23% of Hungary's historic territory.

[7] A small volunteer army was organized mostly from Budapest factory workers and attempts were made to recover the territories lost to neighboring countries, an objective that had widespread support from many working class people in some larger cities, not only those favorable to the new regime.

[8] Initially, thanks to patriotic support from conservative officers, the republican forces advanced against the Czechoslovaks in north Hungary,[9] after suffering a defeat in the east at the hands of the Romanian Army in late April, which led to a retreat on the banks of the Tisza.

[10] In mid-June, the birth of the Slovak Soviet Republic was proclaimed, which lasted two weeks until a Hungarian withdrawal at the request of the Triple Entente.

[13] The Hungarian heads of government applied controversial doctrinal measures in both foreign (internationalism instead of national interests during wartime) and domestic policy (planned economy and heightened class struggle) that made them lose the favor of the majority of the population.

[14] The attempt of the new executive to profoundly change the lifestyle and the system of values of the population proved to be a resounding failure;[15] After the withdrawal from Slovakia, the application of some measures aimed at regaining popular support was ordered, but without great success;[16] in particular, the ban on the sale of alcoholic beverages was repealed, and attempts were made to improve the monetary situation and food supply.

[16] Unable to apply these policies effectively, the republic had already lost the support of the majority of the population between June and July, which led, together with the military defeats, to its downfall.

They prioritized class struggle and loyalty to international communism, framing traditional Hungarian patriotism as an obstacle to revolutionary unity.

They openly dismissed Hungarian patriotism as bourgeois sentiment, rejecting territorial integrity and national pride in their rhetoric, framing such 'patriotism' as a distraction from their ultimate goal: a borderless proletarian state united under international communism.

Károlyi yielded to United States president Woodrow Wilson's demand for pacifism by ordering the unilateral self-disarmament of the Hungarian Army.

During the rule of Károlyi's pacifist cabinet, Hungary lost control over approximately 75% of its former pre-World War I territories (325,411 km²) without armed resistance and was subject to foreign occupation.

[34] For their part, the neighboring countries used the so-called "struggle against communism", first against the capitalist and liberal government of Count Mihály Károlyi and later against the soviet republic of communist Bela Kun, as a justification for their expansionist ambitions.

Kun promised military help and intervention of the Soviet Red Army, which never came, against non-communist Romanian, Czechoslovak, French and Yugoslav forces.

In one crucial incident, a demonstration turned violent on 20 February and the protesters attacked the editorial office of the Social Democratic Party of Hungary's official newspaper called Népszava (People's Word).

On 21 March, Károlyi informed the Council of Ministers that only Social Democrats could form a new government, as they were the party with the highest public support in the largest cities and especially in Budapest.

On 23 March, Lenin gave an order to Béla Kun that Social Democrats must be removed from power, so that Hungary could be transformed into a socialist state ruled by a "dictatorship of the proletariat".

[37] The Communist government also nationalized industrial and commercial enterprises and socialized housing, transport, banking, medicine, cultural institutions, and all landholdings of more than 40 hectares.

[37] The government took steps toward normalizing foreign relations with the Triple Entente powers in an effort to gain back some of the lands that Hungary was set to lose in the post-war negotiations.

[47] The Communist party and their policies had real popular support among only the proletarian masses of large industrial centers, especially in Budapest, where the working class represented a high proportion of the inhabitants.

The Lenin Boys as well as other similar groups and agitators killed and terrorised many people (e.g. armed with hand grenades and using their rifles' butts they disbanded religious ceremonies).

This became known as the Red Terror, and greatly reduced domestic support for the government even among the working classes of the highly industrialized suburb districts and metropolitan area of Budapest.

[49] In June, the Hungarian Red Army invaded the eastern part of the newly forming Czechoslovak state (today's Slovakia), the former so-called Upper Hungary.

The concession eroded support of the communist government among professional military officers and nationalists in the Hungarian Red Army; even the chief of the general staff Aurél Stromfeld, resigned his post in protest.

[55][56][57] In the power vacuum created by the fall of the soviet republic and the presence of the Romanian Army, semi-regular detachments (technically under Horthy's command, but mostly independent in practice) initiated a campaign of violence against communists, leftists, and Jews, known as the White Terror.

[59] Kun himself, along with an unknown number of other Hungarian communists, were executed during Joseph Stalin's Great Purge of the late 1930s in the Soviet Union, to which they had fled in the 1920s.