In September 1944, Soviet forces crossed the Hungarian border. On 15 October 1944, Horthy announced that Hungary had signed an armistice with the Soviet Union. The Hungarian army ignored the armistice. The Germans launched Operation Panzerfaust and, by kidnapping his son (Miklós Horthy, Jr.), forced Horthy to abrogate the armistice, depose the Lakatos government, and name the leader of the Arrow Cross Party, Ferenc Szálasi, as Prime Minister. Szálasi became prime minister of a new fascist Government of National Unity and Horthy abdicated.