He worked closely with Gustav Mahler, whose music he helped to establish in the repertory, held major positions with the Leipzig Gewandhaus Orchestra, New York Philharmonic, Concertgebouw Orchestra, Salzburg Festival, Vienna State Opera, Bavarian State Opera, Staatsoper Unter den Linden and Deutsche Oper Berlin, among others, made recordings of historical and artistic significance, and is widely considered to be one of the great conductors of the 20th century.

[3] In 1896, he was appointed Kapellmeister of the Stadttheater (municipal opera) in Breslau, on the strength of a recommendation from Mahler to the theater's director, Theodor Löwe.

However, Löwe required that before taking up this position the young conductor change his last name from Schlesinger—which literally means Silesian—"because of its frequent occurrence in the capital of Silesia".

He found the town provincial and depressing, and in 1898 took the position of Chief Conductor of the Riga Opera, Russian Empire.

Walter then returned in 1900 to Berlin, where he assumed the post of Royal Prussian Conductor at the Staatsoper Unter den Linden, succeeding Franz Schalk; his colleagues there included Richard Strauss and Karl Muck.

While there, argue Erik Ryding and Rebecca Pechefsky, "Walter's contribution to the history of Wagner performance [was] more significant than many realize.

During the First World War he remained actively involved in conducting, giving premieres to Erich Wolfgang Korngold's Violanta and Der Ring des Polykrates as well as Hans Pfitzner's Palestrina.

[citation needed] In Munich, Walter was a good friend of Cardinal Eugenio Pacelli (later Pope Pius XII).

He made his debut at La Scala in 1926, and was chief conductor of the German seasons at Covent Garden in London from 1924 to 1931.

[citation needed] Walter served as Principal Conductor of the Leipzig Gewandhaus Orchestra from 1929 until March 1933, when his tenure was cut short by the new Nazi government, as detailed below.

[16] Walter was then scheduled to conduct the Berlin Philharmonic on March 20, but its management was warned by Joseph Goebbels that "unpleasant demonstrations" might occur at the concert, and the Propaganda Ministry clarified this by saying that there would be violence in the hall.

[17] Walter later wrote, "The composer of Ein Heldenleben ["A Hero's Life"] actually declared himself ready to conduct in place of a forcibly removed colleague.

[citation needed] Walter's daughter Marguerite "Gretel" (born 1906) was murdered on August 21, 1939, by her husband Robert Neppach, who then killed himself; his motive was jealousy over her growing relationship with the Italian bass singer Ezio Pinza.

He notes, "In old age I have had the good fortune to be initiated into the world of anthroposophy and during the past few years to make a profound study of the teachings of Rudolf Steiner.

Here we see alive and in operation that deliverance of which Friedrich Hölderlin speaks; its blessing has flowed over me, and so this book is the confession of belief in anthroposophy.

From 1946 onwards, he made numerous trips back to Europe, becoming an important musical figure in the early years of the Edinburgh Festival and in Salzburg, Vienna and Munich.

He also coached & accompanied Kathleen Ferrier in London throughout the post war period until her premature death in 1953 & was an ardent fan of her singing.

[26] His final resting place is in the cemetery of Gentilino near Lugano in the Canton of Ticino, Switzerland, in the same grave where his wife and their daughter Gretel had already been buried.

Furthermore, Walter's late recordings focus mostly on older compositions, whereas in his youth he often conducted what was then considered newer music.

Decades later, Walter and the Vienna Philharmonic (with Mahler's brother-in-law Arnold Rosé still a concertmaster) made the first recordings of Das Lied von der Erde in 1936 and of the Ninth Symphony in 1938.

[citation needed] Walter made many highly acclaimed recordings of other great Germanic composers, such as Mozart, Haydn, Beethoven, Schubert, Johannes Brahms, Johann Strauss Jr., and Anton Bruckner, as well as of Bach, Wagner, Schumann, Dvorak, Richard Strauss, Tchaikovsky, Smetana, and others.

Also of great interest are recordings from the 1950s of his rehearsals of Mozart, Mahler and Brahms, which give insight into his musical priorities and into the warm and non-tyrannical manner—as contrasted with some of his colleagues—with which he related to orchestras.