The Brandenburg Concertos by Johann Sebastian Bach (BWV 1046–1051, original title: Six Concerts à plusieurs instruments) are a collection of six instrumental works presented by Bach to Christian Ludwig, Margrave of Brandenburg-Schwedt, in 1721 (though probably composed earlier). They are widely regarded as some of the best orchestral compositions of the Baroque era.
Bach wrote out the music himself for presentation to the Margrave rather than leaving it to a copyist. While he took the opportunity to revise the music, most likely, it was not freshly composed. He appears to have selected the six pieces from concertos he had composed over a number of years while Kapellmeister at Köthen, and possibly extending back to his employment at Weimar (1708–17).
Bach's dedication to the Margrave was dated 24 March 1721. Translated from the original French, the first sentence of Bach's dedication reads:
As I had the good fortune a few years ago to be heard by Your Royal Highness, at Your Highness's commands, and as I noticed then that Your Highness took some pleasure in the little talents which Heaven has given me for Music, and as in taking Leave of Your Royal Highness, Your Highness designed to honour me with the command to send Your Highness some pieces of my Composition: I have in accordance with Your Highness's most gracious orders taken the liberty of rendering my most humble duty to Your Royal Highness with the present Concertos, which I have adapted to several instruments; begging Your Highness most humbly not to judge their imperfection with the rigor of that discriminating and sensitive taste, which everyone knows Him to have for musical works, but rather to take into benign Consideration the profound respect and the most humble obedience which I thus attempt to show Him.
Bach's reference to his scoring the concertos for "several instruments" (Concerts avec plusieurs instruments) is an understatement. Bach used the "widest spectrum of orchestral instruments … in daring combinations," as Christoph Wolff has commented. "Every one of the six concertos set a precedent in scoring, and every one was to remain without parallel." Heinrich Besseler has noted that the overall forces required (leaving aside the first concerto, which was rewritten for a special occasion) tallies exactly with the 17 players Bach had at his disposal in Köthen.
Because King Frederick William I of Prussia was not a significant patron of the arts, Christian Ludwig seems to have lacked the musicians in his Berlin ensemble to perform the concertos. The full score was left unused in the Margrave's library until his death in 1734, when it was sold for 24 groschen (as of 2014, about US$24) of silver. The autograph manuscript of the concertos was only rediscovered in the archives of Brandenburg by Siegfried Wilhelm Dehn in 1849; the concertos were first published in the following year.
The manuscript was nearly lost in World War II, when being transported for safekeeping to Prussia by train in the care of a librarian. The train came under aerial bombardment, and the librarian escaped the train to the nearby forest, with the scores hidden under his coat.
In the modern era these works have been performed by orchestras with the string parts each played by a number of players, under the batons of, for example, Karl Richter and Herbert von Karajan. They have also been performed as chamber music, with one instrument per part, especially by (but not limited to) groups using baroque instruments and (sometimes more, sometimes less) historically informed techniques and practice. There is also an arrangement for four-hand piano duet by composer Max Reger.