Radetzky March
There were no encores in 1939, and sources indicate that encores were not instituted until 1945. Clemens Krauss almost always included "Perpetuum mobile" either on the concert or as an encore. The waltz "The Blue Danube" was not performed until 1945, and then as an encore. The Radetzky March was first performed in 1946, as an encore. Until 1958, these last two pieces were often but not always given as encores. Since that year, their position as twin encores has become inviolable tradition, with two exceptions: