Cantata No. 80: Ein' feste Burg ist unser Gott, BWV80

The cantata unfolds as a set of movements alternating grand choral treatments of the chorale with solo arias and recitatives that comment on its message of trust in God as a defense against evil.

Movement 1 (Chorus): The piece opens with a massive choral fantasia, the four voice parts entering in overlapping waves while the orchestra weaves independent lines around the famous hymn tune, so the melody seems to arrive from every direction at once.

Movement 2 (Duet): A soprano and bass exchange phrases, the soprano floating the chorale tune in long notes while the bass sings a freer, more urgent line underneath, oboe adding a third strand.

Movement 3 (Recitative, bass): A short passage of sung speech sets up the ideas to follow, moving the story forward without a strict beat.

Movement 4 (Aria, bass): A vigorous, martial aria full of forward drive, matching the text's talk of standing firm in battle.

Movement 5 (Chorus): The hymn tune returns here in unison, sung by the full choir and doubled by the orchestra, a moment of unadorned strength after the elaborate music around it.

Movement 6 (Recitative, tenor) and Movement 7 (Duet, alto and tenor): Quieter, more reflective music, voices intertwining over a walking bass line.

Movement 8 (Chorus): The cantata closes with a plain, hymn-like setting of the final verse, the whole ensemble singing the tune in straightforward harmony, as a congregation might have sung it.

Bach wrote this cantata for Reformation Sunday, the Lutheran commemoration of the day in 1517 when Martin Luther is said to have posted his Ninety-Five Theses. The cantata takes its name and its musical backbone from Luther's own hymn "Ein' feste Burg ist unser Gott" ("A mighty fortress is our God"), which Luther wrote and which became an anthem of the Protestant Reformation. Bach assembled the work in Leipzig, drawing on an earlier cantata of his own from his years in Weimar and reworking it to fit the chorale text throughout. It was performed at Leipzig's main churches during his years as cantor there. Later editors and performers, including Bach's son Wilhelm Friedemann, altered the scoring further, adding brass to some movements, so several versions of the piece now circulate. It remains one of Bach's most frequently performed cantatas, especially around Reformation Sunday each year.