these autograph fragments, which are also the only evidence of this version, ended up in three libraries in two continents – the Bibliothèque Polonaise de Paris, the Rossijskaja nacional'naja biblioteka in Saint Petersburg, and the Princeton University Library in New Jersey – and give a very incomplete picture of the version. It is not certain when Bach wrote this version of the cantata. Two fragments are on paper with 1723 watermarks, leading musicologists like Christoph Wolff to conclude that Bach may have written a version of Ein feste Burg ist unser Gott as part of his first cantata cycle. Alfred Dürr proposes a time frame of 1728 to 1731 for its initial composition. The 80b version may have already contained all four stanzas of Luther's hymn. The first stanza appears in the new first movement, the second is a cantus firmus in the second movement (the first movement of the Weimar cantata), and the other two may have been used in the fifth and eighth movements; both of these were chorale settings, as in the later Leipzig version. Wolff writes that Bach thus "may have anticipated the composition of the later series of chorale cantatas". It is not known when Bach composed the elaborate opening movement of the final version. Dürr suggests 1735, because in that year Bach wrote Wär Gott nicht mit uns diese Zeit, BWV 14, which had an opening chorus of a comparable structure and was also based on a hymn by Luther. The final version includes all stanzas of the hymn but is nonetheless not in the format of Bach's second cantata cycle begun in 1724; in that cycle, each chorale cantata relies exclusively on one Lutheran hymn. Bach's son Wilhelm Friedemann Bach, who inherited the scores, later adapted the first and fifth movement, adding parts for three trumpets and timpani. Music Structure and scoring In the later Leipzig version, Bach structured the cantata in eight movements. He scored it for four vocal soloists (soprano (S), alto (A), tenor (T) and bass (B)), a four-part choir (SATB), and a Baroque chamber ensemble of three oboes (Ob), two oboes d'amore (Oa), oboes da caccia or taille (Ta), two violins (Vl), viola (Va), violoncello (Vc), and various instruments playing the basso continuo line. The duration is given as 30 minutes by Dürr. In the following table of the movements, the first column shows the movement number in BWV