During the rule of Count Mihály Károlyi's pacifist cabinet, Hungary lost control over approximately 75% of its former pre-World War I territories, which was about 325,411 km2 (125,642 sq mi), without armed resistance and was subjected to unhindered foreign occupation.

The new government and its supporters had pinned their hopes for maintaining Hungary's territorial integrity on the abandonment of Cisleithania and Germany, the securing of a separate peace, and exploiting Károlyi's close connections in the French Third Republic.

[16] After the Hungarian self-disarmament, Czech, Serbian, and Romanian political leaders chose to attack Hungary instead of holding democratic plebiscites concerning the disputed areas.

On 20 March 1919, the French head of the Entente mission in Budapest gave Károlyi a note delineating the final postwar boundaries, which the Hungarians found unacceptable.

Unknown to Károlyi, however, the Social Democrats had merged with the Hungarian Communist Party; the latter promised that the Russian SFSR would help Hungary to restore its original borders.

After the fall of the Soviet Republic on 1 August 1919, a social democratic government—the so-called "trade union government"—came to power under the leadership of Gyula Peidl.

[20] On 6 August, István Friedrich, leader of the White House Comrades Association—a right-wing, counter-revolutionary group—seized power in a bloodless coup with the backing of the Royal Romanian Army.