Allied Troops March Through Vienna on Anniversary of Liberation -- Red Army troops marching through Vienna during the liberation day parade on Apr 13. A Great military parade was held in Vienna on Apr 13 to celebrate the first anniversary of the liberation of the city by the Red Army. Soviet troops formed the bulk of the marching troops but contingent were provided by British, American and French forces sharing in the occupation of Austria. May 01, 1946. (Photo by Associated Press Photo).