Following the First World War, Hungary underwent a period of profound political upheaval, beginning with the Aster Revolution in 1918, which brought the social-democratic Mihály Károlyi to power as Prime Minister. The Hungarian Royal Honvéd army still had more than 1,400,000 soldiers when Mihály Károlyi was announced as prime minister of Hungary. Károlyi yielded to U.S. President Woodrow Wilson's demand for pacifism by ordering the disarmament of the Hungarian army. This happened under the direction of Béla Linder, minister of war in the Károlyi government. Due to the full disarmament of its army, Hungary was to remain without a national defence at a time of particular vulnerability. During the rule of Károlyi's pacifist cabinet, Hungary lost control over approx. 75% of its former pre-WW1 territories () without a fight and was subject to foreign occupation. The Little Entente, sensing an opportunity, invaded the country from three sides—Romania invaded Transylvania, Czechoslovakia annexed Upper Hungary (today's Slovakia), and a joint Serb-French coalition annexed Vojvodina and other southern regions. In March 1919, communists led by Béla Kun ousted the Károlyi government and proclaimed the Hungarian Soviet Republic (''Tanácsköztársaság''), followed by a thorough Red Terror campaign. Despite some successes on the Czechoslovak front, Kun's forces were ultimately unable to resist the Romanian invasion; by August 1919, Romanian troops occupied Budapest and ousted Kun.