The String Quartets, Op. 50 (Hob. III/44–49, L. 36–41), were composed by Joseph Haydn in 1787. The set of six quartets was dedicated to King Frederick William II of Prussia. For this reason the set is commonly known as the Prussian Quartets. Haydn sold the set to the Viennese firm Artaria and, without Artaria's knowledge, to the English publisher William Forster. Forster published it as Haydn's Opus 44. Haydn's autograph manuscripts for Nos. 3 to 6 of the set were discovered in Melbourne, Australia, in 1982.

Each of the six quartets in the set has four movements, and in each case the movements are ordered in a conventional fast–slow–minuet–fast sequence.

The set was Haydn's first complete set of quartets since the Opus 33 set of 1781. While the Opus 33 set was apt for broad public consumption, the Opus 50 set is more serious and experimental. It is perhaps because of the Opus 50's intellectual character that other sets among Haydn's mature quartets have received more attention from performers.

History

Haydn conceived of what became the Opus 50 set in a letter to the publishing house Artaria in 1784, although he then put the project on hold for the Paris symphonies and The Seven Last Words of Christ. He started work in 1787, composing the first two quartets in February. In April, Haydn received a letter from King Frederick William II of Prussia, praising Haydn for the copies of the Paris symphonies that he had sent. The letter enclosed a golden ring. Haydn sought to return the favour by dedicating the Opus 50 set to the King, and Artaria acceded to Haydn's request to do so.

The history of the publication of Opus 50 set betrays one of the more remarkable examples of Haydn's financial and commercial impropriety. Haydn hurriedly completed the set by September 1787, when he sent the fifth quartet to Artaria. Meanwhile, in August, he had offered the set to the English publisher William Forster, who duly printed the six quartets before Artaria did. Haydn was deceiving both publishers: the offer to Forster was unbeknown to Artaria, while Haydn misled Forster into believing that no one else had been offered the set. Artaria learned of the Forster deal but published the set anyway, in December 1787, as Haydn's Opus 50.

In 1982, the original autograph manuscripts of the Nos. 3 to 6 of the set were discovered at a festival arranged in Melbourne, Australia, for the 250th anniversary of Haydn's birth. After a concert at the festival, a woman presented the manuscripts in a plastic shopping bag to the conductor Christopher Hogwood. The Haydn scholar Georg Feder, who was visiting Australia at the time, then verified the scores to be the authentic original manuscripts of the four quartets. It emerged that the woman who presented the manuscripts to Hogwood had inherited them, through successive generations, from an English colonel who had purchased them at an 1851 auction before emigrating to New Zealand. The colonel's heirs were evidently unaware that they owned the only original versions of the quartets in Haydn's pen. Until the 1982 discovery, publishers had been working from incomplete or non-original editions.

Overview The six quartets in the set are: Quartet No. 36 in B major, Op. 50, No. 1, Hob. III/44 Quartet No. 37 in C major, Op. 50, No. 2, Hob. III/45 Quartet No. 38 in E major, Op. 50, No. 3 Hob. III/46 Quartet No. 39 in F minor, Op. 50, No. 4, Hob. III/47 Quartet No. 40 in F major ("Dream"), Op. 50, No. 5, Hob. III/48 Quartet No. 41 in D major ("The Frog"), Op. 50, No. 6, Hob. III/49

In Haydn's previous two sets of quartets, the Opus 20 ("Sun") and Opus 33 ("Russian"), he adopted a variety of cyclical structures, particularly in the alternate placement of the slow movement as the second or third movement. But in the Opus 50 set, each quartet follows the same fast–slow–minuet–fast sequence. The set is also characterised by a high degree of monothematicism (the use of a single theme within a movement). In a number of movements, including sonata form movements and minuets and trios, Haydn eschews presenting a second and contrasting theme and instead elects to explore the full potential of the primary theme.

The set's dedicatee, King Frederick William II, was a capable amateur cellist. The set contains a number of striking passages for the cello, including in its opening of the first movement of No. 1 and its leading passages in the slow movements of Nos. 2 and 3.

Opus 50, No. 1 The first quartet of the set, in B major, is numbered III/44 in the Hoboken catalogue. Its movements are listed below, with their opening themes.

First movement:

Second movement:

Third movement:

Fourth movement

The first movement is in cut common () time. It starts with the cello, alone, playing eight quarter notes on the same B. It is not until the third measure of the movement that the violins and viola enter. The cello's eight throbbing notes act as more than an introduction. They reappear at critical junctures throughout the movement, including at the beginning of the development and recapitulation sections, illustrating that they are part of the movement's primary thematic material. The melody that follows the eight cello notes echoes Mozart's Violin Sonata K.454 and is echoed in Beethoven's String Quartet No. 1 (Op. 18, No. 1).

The first movement caught the admiration of the pianist and scholar Charles Rosen, who devoted several pages of his book The Classical Style (1997) to it. Rosen suggests that essentially everything in this movement is musically derived from just two elements: (a) the ostinato notes repeated by the cello at the opening, and (b) the up-down sequence played by the first violin and viola in the third and fourth bars. Both (a) and (b) are repeated played in varied forms and in different keys. Rosen provides an annotated version of the entire exposition section (pp. 121-131) to show how it is derived from (a) + (b). He concludes:

Neither (a) nor (b) alone is sufficient, but from the opposition between them and from their shape Haydn derives his larger structure. There are no tunes, few rhythmic surprises, fewer dramatic harmonies. Yet is it fascinating and witty music, in which Haydn, intent on dazzling us with his technique, makes splendid bricks with hardly any straw at all.Rosen (1997:124)

The second movement is in E major and strophic form, with a statement of a theme followed by three variations (the second of which is in E minor) and a coda. Haydn used a similar design for the slow movement of the Opus 20, No. 4 quartet. In 1793 the poet Gabriele von Baumberg set the movement's theme to words, for inscription on a monument honouring Haydn in the composer's home town of Rohrau, Austria.

The third movement, a minuet and trio, features motivic elements that hark back to the previous two movements. In the trio, Haydn uses off-beat entries and second-beat sforzandos to disrupt what would otherwise be a regular and conventional triple metre.

The fourth movement, in sonata form but with characteristics of a rondo, is replete with Haydnesque false recapitulations and conclusions. In one example, the music lands in the tonic at the end of the recapitulation and apparent coda, and is followed by two measures of complete silence, creating an illusion of finality. However, the main theme is then reprised, and the real conclusion to the work follows some 20 measures later.

Opus 50, No. 2 The second quartet of the set, in C major, is numbered III/45 in the Hoboken catalogue. Its movements are listed below, with their opening themes.

First movement:

Second movement:

Third movement:

Fourth movement:

The first movement is in time, hitherto uncommon among Haydn's opening movements. In this movement, Haydn departs from the monothematic approach that characterises many of his other sonata form movements in the set. The exposition presents two clearly distinct themes: the first in the tonic and the second in the dominant.

The second movement, in F major and marked "adagio cantabile", commences with the statement of the primary theme by the second violin, before it is taken up by the first violin in the ninth measure. The first violin part enjoys a move into a high register in the movement's central section as well as an elaborate solo passage towards the end of the movement. The movement's central section also features a five-measure passage of sixteenth notes for the cello, perhaps specially written for the opus's cellist dedicatee.

The opening measure of the minuet, after an upbeat, is a descending C-major triad (G–E–C) played by the first violin. The trio inverts this opening with an ascending triad (C–E–G) played by the second violin.

The finale is in sonata form. It features significant developments of a simple motif, and considerable dialogue between the four parts. The finale also contains a high degree of chromaticism, a feature that links the four movements of the work. The musicologist W. Dean Sutcliffe points to the recurrence of C at key points in each movement, serving at different times to create dissonance, to commence modulation away from the tonic, or, as in the case of the finale, as a device for inflection.

Opus 50, No. 3 The third quartet of the set, in E major, is numbered III/46 in the Hoboken catalogue. Its movements are:

First movement:

Second movement:

Third movement:

Fourth movement:

This is a concise work, in terms of its duration, the economy of thematic material presented, and also the narrow registers within which the four parts operate. The first movement is in time and a monothematic sonata form. The development and recapitulation sections feature an example of Haydn's musical jokes. In this case he tinkers with the movement's sonata form by reference to an historical variation of it. The recapitulation starts only with a statement of the second phrase of the movement's theme, which is in the dominant. This would have been a common technique earlier in the eighteenth century that, in this instance, is liable to confuse the unknowing listener looking for the statement of the first phrase of the theme in the tonic. It is not until 27 measures later that the listener is presented with a more emphatic reprise, which is actually a coda. The coda involves the statement of the main theme in the tonic that the listener might have been expecting, and it does so after two measures of pointed silence.

The form of the second movement, an Andante in B major, is undefinable. The movement involves elements of a theme and variations, but also has characteristics of both a ternary form movement and a rondo. Unlike a conventional theme and variation movement, the minor mode variation is placed immediately after the statement of the theme; normally, the minor mode theme would be held back for later in the movement. The second variation involves very little actual variation, and is closer to a literal re-statement of the theme that one would see in ternary form or a rondo. Also unconventionally, the second and third so-called variations are separated by an eight-measure free-form passage. The cello enjoys a prominent role throughout the movement, with the viola often substituting as the bass accompaniment. The cello also presents the movement's opening theme.

The one exception to the compactness of the quartet comes in the minuet. The minuet's first half is a standard 12 measures, but the second half is an unusually long 44 measures and involves harmonic excursions deep into the flat-side keys. The trio echoes the first and fourth movements by commencing with a B upbeat leading to an E.

The finale completes the interconnectedness of the work with a theme audibly similar to those of the first movement and the minuet and trio. The movement is the most economical of all: the exposition and development commence with nearly identical passages and conclude in exactly the same way.

Opus 50, No. 4