Style polarized around Wagner (neo-romantics, including Strauss, Mahler, Wolf, Scriabin, and the nationalists: Sibelius in Finland, Elgar in England, Rachmaninov and Rimsky-Korsakov in Russia, et.al.) and Debussy (impressionists, including Ravel, Roussel, Delius, Loeffler and Dukas).
Impressionists
The first big break with German Romanticism came in the works of Claude Debussy (1862-1918) whose harmonic idiom included
(a) unprepared and unresolved dissonances,
(b) frequent use of pedal point and ostinato,
(c) parallel chords including parallel fifths, fourths and octaves,
(d) pentatonic and whole-tone scales, and
(e) avoidance of the leading tone.
These devices served to blur tonality and to emphasize chordal color over harmonic function in deliberate contrast to neo-romantic style.
Orchestral Music
Impressionistic style included
(a) emphasis on woodwinds, muted brass and harp,
(b) wordless choruses (Debussy's Nocturnes, 1899, Ravel's Daphnis et Chloe, 1912, Roussel's Evocations, 1912),
(c) kaleidoscopic, blurred forms,
(d) vague, irregular rhythm and
(e) descriptive titles.
The major works were (1) symphonic poems, Debussy's Prelude à l'apres-midi d'un faune (1894) and the more realistic Sorcerer's Apprentice (1897) of Paul Dukas (1865-1835),
(2) groups of symphonic poems, Debussy's La Mer (1905) and Images pour orchestre (1906), and
(3) suites, Maurice Ravel's (1875-1837) Rapsodie espagnol (1907).
French Opera
Pelléas et Mélisande (1902) by Debussy set a symbolist play by Maeterlinck to uniquely suitable impressionist music with extended orchestral interludes and recitative which imitated French speech patterns. Other operas were the realistic Louise (1900) by Gustave Charpentier (1860-1956), Thais (1894) by Massenet, and Revel's L'Heure espagnole (1910).
French Song
Impressionism was represented by Debussy's Fete galantes (1892, 1904), Chanson de Bilitis (1897), Ravel's Histoire Naturelles (1906) and his orchestral song cycle Shéhérazade (1903). Faure's important cycles in an older style were La Bonne Chanson (1892-3) and La Chanson d'Eve (1907).
Chamber Music
Both Debussy, (1893) and Ravel (1903) wrote string quartets.
Piano Music
Descriptive titles which set a mood were important in Debussy's Estampes (1903), Images I (1905), II (1907) and Preludes I (1910) and II (1913), and Ravel's Jeux d'eau (1901) and Miroirs (1905). Eric Satie's (1866-1925) Three Pieces in the Shape of a Pear (1903) and Dried-up Embryos (1913) ridiculed these impressionist titles.
Neo-Romantics
Expression through tonality and modulation, begun by Haydn, reached its final phase in works characterized by extremes of chromaticism and free modulation, enormous orchestras, emotional realism and the long surging line.
Symphonic Poem
Richard Strauss (1864-1949) used both philosophical programs, Tod und Verklärung (1889) and Also sprach Zarathustra (1896), and descriptive programs, Don Juan (1899), Till Eulenspiegel (1895), Don Quixote (1897), Ein Heldenleben (1898), Sinfonia Domestica (1903) and Alpensymphonie (1915). His strongest feature was the virtuosic use of the orchestra.
Jean Sibelius (1865-1957) also composed a number of symphonic poems based on the Finnish national epic, Finlandia (1899).
Symphony
Gustav Mahler (1860-1911) also excelled at virtuosic orchestration in his ten symphonies, including No. 2 "Resurrection" (1895), No. 4 (1901) and No. 8 "of a Thousand" (1910). He typically included orchestral songs (Nos. 2, 3, and 4), augmented his often huge orchestra with chorus (Nos. 2, 3, and 8), used folk-like melodies and varied the number of movements. Early programs were later suppressed. Sibelius' most important symphonies were No. 2 (1902) and No. 4 (1911).
Orchestral Variations
Unlike Brahms, orchestral variations in this generation did not retain the structure in each variation. These were Vincent D'Indy's (1851-1931) Istar Variations (1896) and Edward Elgar's (1857-1934) Enigma Variations (1899).
Piano music
The limits of romantic piano idiom were reached in the ten sonatas of Alexander Scriabin (1872-1915) and the preludes, Op. 3, No. 2 (1892), Op. 23 (1904) and Op. 32 (1910), and Piano Concertos No. 2 (1901) and No. 3 (1909) of Sergei Rachmaninov (1873-1943).
Orchestral Song Cycle
Closely related to his symphonies in style and structure were Mahler's Lieder eines fahrenden Gesellen (1883-84), Kindertotenlieder (1902) and Das Lied von der Erde (1908) for tenor and contralto.
Lied
The new generation began composing songs in the 1880's and included Mahler, Strauss (composing 1882-1901), and Hugo Wolf (1860-1903) who published his songs in volumes by a single poet: Mörike (1888), Eichendorff (1888), Goethe (1889), Spanisches Liederbuch (1890), Italienische Liederbuch (1891, '96) and Michaelangelo (1897).
German Opera
Wagnerian principles of continuous music and use of leitmotives were found in the dissonant and dramatically violent Salome (1905) and Elektra (1909) by Strauss.
Italian Opera
Verismo was the operatic version of literary realism, shown in the use of naturalistic recitative, the disappearance of coloratura and commonplace, often violent subject matter. The operas were Cavalleria rusticana (1890) by Pietro Mascagni (1863-1945), I Pagliacci (1892) by Ruggiero Leoncavallo (1858-1919), and Manon Lescaut (1893), La Bohème (1896), Tosca (1900) and Madame Butterfly (1904) by Giacomo Puccini (1858-1924).
Russian Opera
Russian opera continued in Sadko (1897) and Le Coq d'or (1909) by Rimsky-Korsakov.
Choral Music
Important choral works were Elgar's oratorio Dream of Gerontius (1900) and Guerrelieder (1901), a cantata by Arnold Schoenberg (1874-1951).
American Jazz
Ragtime for piano by Scott Joplin (1868-1917) flourished c. 1897-1910 with an upbeat tempo and syncopated right hand, including "Maple Leaf Rag" (1899) and his opera Treemonisha (one performance in 1915).