German composer, conductor and violoncellist of much ability, still more noted as an editor and teacher of music. He was born at Berlin; younger brother of Eduard Rietz. He studied the cello under Schmidt, Bernhard Romberg, and Moritz Ganz, and composition under Zelter; at sixteen he entered the orchestra of the Konigstadter Theatre, and while there composed the incidental music to Lorbeerbaum und Bettelstab, a play by Holtei. In 1834 he became assistant conductor to Mendelssohn at the Dusseldorf Opera, succeeding him as chief conductor the next year. In 1836 he was appointed town musical director, which included the conductorship of the Choral Society, of the music at the Andreaskirche and of the subscription concerts, a post which he held for twelve years, attaining a high reputation for his conducting, and continuing his solo playing by appearances at various towns in that vicinity. In 1847 he was called to Leipsic as conductor of the Singakademie and the Opera, and the next year of the Gewandhaus Orchestra, also professor of composition at the Conservatory; in 1854 he resigned the directorship of the Opera. In 1860, after another dozen years of work, he received the appointment of Court chapelmaster at Dresden, where he had charge of the music at both the Opera and the Roman Catholic Church and a little later became artistic director of the Conservatory. The title of general musical director was conferred on him in 1874. He died at Dresden, just a few weeks before his projected retirement. As a composer Rietz was a classicist, and to him Mendelssohn had spoken the last word in music. While scholarly and intellectual in all his work. Julius Reitz's music was somewhat deficient in inspiration and originality.
Of his operas, Das Madchen aus der Fremde, Jery und Bately, Der Korsar, and Georg Neumark, the last two were failures. His incidental music to dramas by Goethe and other writers was more successful; but several of his instrumental works surpassed them. Among these were his symphonies in E flat and G minor, his Lustspiel overture and concert overture in A minor, and also choral works with orchestra: Altdeutscher Schlachtgesang and a setting of Schiller's Dithyrambe. Besides these more prominent works are a third symphony, three more overtures; five concertos; sonatas; a concertstuck for orchestra; a capriccio; a string quartet; other music for piano; songs, choruses; masses, psalms, and other choral music. His editions of Mozart's symphonies and operas, of Beethoven's overtures and symphonies, and of Mendelssohn's complete works, are very valuable; most of this work was done for Breitkopf und Hartel, and he also edited works for the Bach and Handel Societies in Germany, his additional accompaniments to the scores of the latter composer being regarded as of a high order. While a thorough musician and an able conductor Rietz's reputation is that of a musical editor and teacher, numbering among his pupils Bargiel, Dessoff, Radecke, Dudley Buck, Sir Arthur Sullivan, and others. For half a dozen different times he was conductor of the Lower Rhine Festivals.