The Allied occupation of Austria ended in 1955 and sovereignty was restored via the Austrian State Treaty.
At the end of the war, Austria and Vienna were divided into 4 zones of occupation, following the terms of the Potsdam Conference. With the permission of the Soviet forces, a provisional government was established in Vienna on April 29 and the first post-war legislative election took place on November 25, 1945. Karl Renner, the first Chancellor of post-World War One Austria, was appointed as Austria's first Chancellor, this appointment lasted until the end of 1945, when Renner became the first President of the Second Republic.
On May 15, 1955, the Austrian State Treaty was signed, officially establishing Austrian independence and sovereignty. The treaty was enacted on July 27 and the last Allied troops left the country on 25 October. On the following day, 26 October, the Declaration of Neutrality was enacted, establishing Austria as a permanently neutral country. For this reason, October 26 is Austria's national holiday.