[Illustration: JOSEPH STRAUSS. From a lithograph by Maurin, at the Paris Opera Library.] For more than a quarter of a century Strauss continued to devote himself to the creation and the conducting of dance music; and the number of his pieces in this _genre_ rose to over three hundred. His opus 314 was the "Blue Danube Waltz," which has since become famous not only as a sort of second Austrian national hymn, by the side of Haydn's "Gott erhalte Franz den Kaiser," but as the transition to a new sphere of activity. For it was _a vocal waltz_, being written for male chorus and orchestra; and just as Beethoven's choral symphony, according to Wagner, pointed to the necessity of the music-drama, so it seems that Strauss used this vocal waltz as a transition to the Viennese operetta, a new style of stage-music which owes its present form and vogue chiefly to his genius. It is said that Strauss's wife was largely instrumental in making him change his sphere from the humble dance hall to the more ambitious theatre. She was a famous singer and actress, named Jetty Treffz, when Strauss married her in 1863, and if she was really responsible for her husband's "new departure," the world owes her a large debt of gratitude. She died in April, 1879, and toward the close of the same year Strauss married the dramatic singer, Angelica Dittrich. Two years after his first marriage he sent Eduard in his place to St. Petersburg, and in 1870 he also resigned his position as conductor of the court balls in his brother's favor. But if any one fancied that he had lost his interest in music, or, like Rossini, intended to retire from active life when his triumph was at its height, the error was soon made manifest; for in 1871 Johann Strauss appeared on the boards of the Theater an der Wien with something which no one had ever expected of him--an operetta. "Indigo" was its name, and its reception was sufficiently gratifying to encourage him to try another and still another, with ever-increasing success. [Illustration: JOHANN STRAUSS (Senior). Caricature by Dantan in the Carnavalet Museum, Paris.] Some of these operettas--especially _The Bat_ (_Fledermaus_), the _Merry War_, the _Queen's Lace Handkerchief_, and the _Gypsy Baron_--became enormously popular in Austria, Germany and the United States (where they have been sung successfully in both German and English), and if anything had been needed to make the "Waltz King" known to the whole world, and admired by everybody, these operettas would have brought about that result. * * * * *