Hungarian Democratic Republic
In the aftermath of World War I which had led to the collapse of the Austro-Hungarian Empire, half of the Hungarian population was cut away from Hungary by the Treaty of Trianon and made part of surrounding nations. In 1918–19, Budapest was shaken by two revolutions: the Aster Revolution brought about the Hungarian Democratic Republic, which was followed by the Hungarian Soviet Republic, a short-lived Communist regime led by Béla Kun, followed by two years of White Terror. The Hungarian–Romanian War of 1919 ended with the Romanian occupation of parts of Hungary proper, including Budapest in August 1919, and the establishment of the Kingdom of Hungary, led by Miklós Horthy, the self-appointed regent for the exiled King Karl IV (see the conflict of Charles IV with Miklós Horthy). His domain and regency was characterized by gala balls as well as hunger marches by the poor, of nationalism and anti-Semitism by inheritance, again inherited by joining the wrong side (the Nazis), who promised the sweet reward of re-joining of the Hungarian nation as a whole in the post-Trianon era. Yet Horthy was considered a moderate compared to the fascist Arrow Cross Party, whose power grew as World War II raged across Europe.