Franz Schubert's final chamber work, the String Quintet in C major (D. 956, Op. posth. 163) is sometimes called the "Cello Quintet" because it is scored for a standard string quartet plus an extra cello instead of the extra viola which is more usual in conventional string quintets. It was composed in 1828 and completed just two months before the composer's death. The first public performance of the piece did not occur until 1850, and publication occurred three years later in 1853. Schubert's only full-fledged string quintet, it has been praised as "sublime" and as possessing "bottomless pathos," and is generally regarded as Schubert's finest chamber work as well as one of the greatest compositions in all chamber music.
The string quintet was composed in the summer or early autumn of 1828, at the same time as Schubert composed his last three piano sonatas and several of the Schwanengesang songs. Schubert completed it in late September or early October, just two months before his death. Schubert submitted it to one of his publishers, Heinrich Albert Probst, for consideration, saying that "finally I have written a quintet for 2 violins, 1 viola, and 2 violoncello ... the quintet rehearsal will only begin in the next few days. Should any of these compositions by any chance commend themselves to you, please let me know." Probst replied, asking only to see some of Schubert's vocal works and requesting more popular piano music. Even at this very late stage in Schubert's career, it is obvious that he was regarded as a composer who mainly focused on songs and piano pieces, and was definitely not taken seriously as a chamber music composer. The work remained unpublished at the time of Schubert's death in November 1828, and indeed waited twenty-five years for its first publication in 1853. Its first known public performance occurred only three years earlier, on 17 November 1850 at the Musikverein in Vienna.
The work is the only full-fledged string quintet in Schubert's oeuvre. When he began composing his string quintet, Schubert had already composed an impressive body of chamber music for strings, including at least fifteen string quartets, most of which were composed for domestic performance by his family's string quartet.
Schubert selected the key of C major in a possible gesture to two composers he greatly admired, Mozart and Beethoven, both of whom wrote string quintets in that key, Mozart's String Quintet No. 3 in C major, K. 515 and Beethoven's String Quintet, Op. 29 in C major. According to Charles Rosen, the opening theme of Schubert's work emulates many characteristics of the Mozart quintet's opening theme, such as decorative turns, irregular phrase lengths, and rising staccato arpeggios (the latter appear only in Schubert's recapitulation).