Allegro in B♭ for Violin and Piano (fragment; Stadler completion), K. 372
par Wolfgang Amadeus Mozart
Mozart’s Allegro in B♭ major (K. 372) is a fragmentary violin-sonata movement from Vienna in 1781, surviving in autograph only in part and commonly performed in a completion by Abbé Maximilian Stadler (1748–1833) [1]. The piece offers a brief, vivid glimpse of Mozart at 25—newly established in Vienna—working in the brilliant, conversational idiom of his keyboard-and-violin chamber music [1].
What Is Known
The surviving source is a fragment of a sonata movement in B♭ major for violin and piano, generally dated to Vienna (1781) [1]. The version most often encountered today incorporates a completion by Abbé Maximilian Stadler; a telling detail is that, in at least one autograph leaf, the final staves are in Stadler’s hand rather than Mozart’s—evidence of direct editorial intervention at the ending [2]. Modern editions and performances therefore present a mixed text: Mozart’s fragment up to the break, and Stadler’s attempt to supply what is missing [1]. In practical terms, issues of style and balance—especially how conclusively the exposition and cadence are rounded off—depend on Stadler’s solutions rather than on securely transmitted Mozart material.
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Musical Content
What survives is an Allegro movement in common time (C) in B♭ major, written in the familiar duo-sonata medium of keyboard with violin [1]. The musical surface is bright and propulsive, with the violin partnering rather than merely doubling: short melodic figures are passed between the instruments, and the texture suggests the sonata-allegro world Mozart was cultivating in Vienna, where chamber music increasingly mirrors the rhetoric of his larger concerted style. Because the ending is partly or wholly supplied by Stadler, performers and listeners should hear the close not as documentary evidence of Mozart’s final intention, but as a historically important—and often persuasive—completion that enables the fragment to function in the concert hall [1].
[1] Digital Mozart Edition (Mozarteum): NMA table of contents listing “Movement of a Sonata in B flat … completed by Maximilian Stadler” (K. 400/372a; fragment tradition relevant to K. 372 context).
[2] Henle Blog (2013): discussion of Stadler’s hand in autograph materials; notes that last staves are by Stadler for the “Allegro of a Sonate … Fragment, K. 372,” with shelfmark information.
[3] IMSLP work page for “Allegro in B-flat major, K.372,” noting the fragment status and Stadler completion in editions.