Operation Margarethe was the occupation of Hungary by Nazi German forces during World War II, as it was ordered by Hitler on 12 March 1944. A plan for the occupation of Romania was devised under the name Operation Margarethe II but was never carried out.
The Hungarian Prime Minister Miklós Kállay, with the knowledge and approval of Regent Miklós Horthy, had been discussing an armistice with the Allies. German dictator Adolf Hitler found out about these discussions and, feeling betrayed by the Hungarians, ordered German troops to implement Operation Margarethe to capture critical Hungarian facilities, on 12 March 1944.
Hitler invited Horthy to the palace of Klessheim, outside of Salzburg, Austria on March 15. While they conducted their negotiations, German forces quietly moved into Hungary. The meeting was merely a ruse to keep Horthy out of the country and leave the army without orders. Negotiations between Horthy and Hitler lasted until the 18th, when Horthy boarded a train to return home.
When he arrived in Budapest, it was German soldiers who greeted him. Horthy was told that Hungary could only remain sovereign if he removed Kállay in favour of a government that would cooperate fully with the Germans. Otherwise, Hungary would be subject to undisguised occupation. Knowing the latter meant a gauleiter who would treat Hungary no differently than an occupied enemy country, Horthy appointed Döme Sztójay as Prime Minister to appease German concerns. The occupation was a complete surprise and resulted in it being quick and bloodless. The initial plan was to immobilise the Hungarian army, but with Soviet forces advancing from the north and east, and with the prospect of British and American forces invading the Balkans, they decided to retain the forces, sending a portion to defend the passes through the Carpathians.