During the course of his lifetime (1770–1827), Ludwig van Beethoven enjoyed relationships with many of his musical contemporaries.
 Beethoven was famously difficult to get along with, and the history of his relationships with contemporaries is littered with arguments, misunderstandings, and reconciliations.
 Beethoven had well-known fallings out with his one-time teacher, Joseph Haydn, with the piano virtuoso and composer Johann Nepomuk Hummel, and the German composer Carl Maria von Weber.
Wilhelm von Lenz (born 20 May 1809 in Riga - died 7 January 1883 in Saint Petersburg) was a Baltic German Russian official and writer.
 Wilhelm von Lenz was a friend of many mid-century Romantic composers, including Franz Liszt, Frédéric Chopin and Hector Berlioz, Lenz's most important and influential work was an early biography of the German composer Ludwig van Beethoven, entitled "Beethoven et ses trois styles" (1855), written in response to the disparagement of Beethoven by Alexander Ulybyshev in his "Nouvelle biographie de Mozart" (1843).
 Lenz promoted the idea (already suggested by earlier figures such as François-Joseph Fétis) that Beethoven's musical style be divided into three characteristic periods.
 Lenz's periodisation, with minor changes, is still widely used today by musicologists in discussing Beethoven's compositions.
Ludwig van Beethoven is a series of sculptures of Ludwig van Beethoven by German-American sculptor Henry Baerer.
 Versions are displayed in Central Park in New York City, Golden Gate Park in San Francisco, and Prospect Park in Brooklyn.
 The sculpture in Central Park was dedicated on July 22, 1884.
 It includes two bronze statues, including a bust of Beethoven and an allegorical female figure on a polished Barre Granite pedestal.
Ludwig van (full title: "Ludwig van: A report"; German: "Ludwig van: ein Bericht") is a black-and-white German film by Mauricio Kagel.
 Filmed in 1969, it was first screened the following year.
 The work was commissioned by Westdeutscher Rundfunk for the bicentennial celebrations of the birth of Ludwig van Beethoven in 1970.
 The film examines the reception of the composer and his works and how he has become a consumer product of the culture industry.
 The soundtrack is an arrangement of fragments of Beethoven's works, modified as if heard by the deaf composer himself; it is distinct from Kagel's 1970 composition "Ludwig van".
 Prominent contemporary artists including Dieter Roth, Stefan Wewerka (), Robert Filliou, and Joseph Beuys were involved in the design.
 According to "Gramophone", "at first it’s a laugh a minute ... then Kagel's film turns dark".
The Beethoven "Gesamtausgabe" is the first collected edition of the works of Ludwig van Beethoven.
 Its full title is "Ludwig van Beethovens Werke: vollständige kritisch durchgesehene überall berechtige Ausgabe" (which roughly translated means "Ludwig van Beethoven's Works: complete, critical, thoroughly revised, authorized edition").
 It was published between 1862 and 1865, with a supplementary volume appearing in 1888.
Heinrich August Marschner (16 August 1795 – 14 December 1861) was the most important composer of German opera between Weber and Wagner.
Ludwig van Beethoven the Elder, also Ludovicus van Beethoven and Lodewijk van Beethoven (January 5, 1712 – December 24, 1773) was a professional singer and music director, best known as the grandfather of the composer Ludwig van Beethoven.
Johanna van Beethoven (née Reiß [Reiss]; 1786–1869) was the sister-in-law of the composer Ludwig van Beethoven.
 She is remembered for the bitter custody battle between herself and the composer over her son Karl, one of the most ugly and traumatic episodes in the composer's life.
Hans Heiling is a German Romantic opera in 3 acts with prologue by Heinrich Marschner with a libretto by Eduard Devrient, who also sang the title role at the première at the Königliche Hofoper (now Berlin State Opera), Berlin, on 24 May 1833, and went on to become Marschner's most successful opera.
 The opera brought the composer a considerable reputation, although this did not materially affect his position in Hanover, where he was music director of the Court Theatre.
 Like Marschner's other great success, "Der Vampyr", the plot of "Hans Heiling" makes great use of supernatural elements.
 As with several of his operas, "Hans Heiling" is based on a folk legend.
Ludwig van Beethoven ( , ; ] ; baptised 17 December 177026 March 1827) was a German composer and pianist.
 A crucial figure in the transition between the Classical and Romantic eras in Western art music, he remains one of the most famous and influential of all composers.
 His best-known compositions include 9 symphonies, 5 piano concertos, 1 violin concerto, 32 piano sonatas, 16 string quartets, his great Mass the "Missa solemnis", and one opera, "Fidelio".

Question: In between Ludwig van Beethoven and Heinrich Marschner who was the most important composer of German opera between Weber and Wagner?
Answer: Heinrich August Marschner