order to address increasingly frequent skirmishes along the Hungarian–Romanian line of control, the Paris Peace Conference decided on 26 February 1919 to allow Romanian troops in an area beyond the demarcation line established by the armistice of Belgrade, and set up an additional neutral zone to be occupied by Allied forces other than Romanians. This established the "temporary frontier" along the Arad–Carei–Satu Mare line. Vix was tasked with presenting the demand to the Hungarian authorities, along with the request that their withdrawal must start on 23 March and be completed within ten days. On 20 March 1919, Hungary was presented with the demand that became known as the Vix Note. In response, Károlyi resigned, and a revolutionary council established by the Social Democratic Party and the Communist Party assumed power. The council abolished the First Hungarian Republic, replacing it with the Hungarian Soviet Republic. In the summer of 1919, Soviet Hungary fought a war against Czechoslovakia and a war against Romania, resulting in the downfall of the communist regime and the Romanian capture of Budapest on 4 August. France urged the Army of the Kingdom of Serbs, Croats and Slovenes to move against the Hungarian Soviet Republic by advancing north from Bačka, but no such military intervention ever took place. In June 1919, Banat was partitioned by the Allies against Romanian complaints that this was contrary to the promise of the entire region being awarded to Romania under the Treaty of Bucharest. By December, the Romanians gave way to diplomatic pressure and agreed to the Kingdom of Serbs, Croats and Slovenes receiving the western part of Banat. On 12 August, the armed forces of the Kingdom of Serbs, Croats and Slovenes occupied Prekmurje. The move had been authorised by the Paris Peace Conference a month earlier as compensation for the kingdom's contribution to the suppression of the Hungarian Soviet Republic. A short-lived republic was proclaimed in Prekmurje in late May, but was suppressed by Hungarian troops in early June. On 4 June 1920, the Paris Peace Conference produced the Treaty of Trianon as the peace agreement between the Allies and Hungary. Territorial changes under the treaty awarded Transylvania, Crișana, the southern part of Maramureș and the eastern part of Banat to Romania – exceeding the armistice of Belgrade demarcation line in Romania's favour. The Kingdom of Serbs, Croats and Slovenes formally received Bačka, the western part of Banat, and the