Bach was born on March 21, 1685 (Julian calendar; March 31 Gregorian), in the Thuringian town of Eisenach, the youngest child of town musician Johann Ambrosius Bach. Orphaned by age ten, he was raised by his elder brother and trained on organ and violin. He went on to compose over a thousand works, from the Brandenburg Concertos to the Mass in B minor, becoming the towering figure of the Baroque era and a foundational influence on nearly all subsequent Western music.
Eisenach in 1685 was a modest Thuringian town, but it sat within a dense web of Bach relatives who had supplied organists, town pipers, and court musicians to the region for generations. Johann Sebastian's father taught him violin and basic music theory before dying when the boy was nine; his mother had died months earlier. The orphaned ten-year-old moved in with his older brother Johann Christoph, an organist in Ohrdruf, who continued his musical education, reportedly locking away a book of keyboard scores that young Sebastian supposedly copied out by moonlight over six months.
Bach never left German-speaking lands, never achieved wide fame in his lifetime beyond his reputation as a formidable organist and improviser, and spent his final decades as a church musician in Leipzig producing weekly cantatas on tight deadlines. Only in the nineteenth century, championed by figures like Felix Mendelssohn, did his reputation swell to its modern scale.
Because the Julian calendar was still in use in Protestant Germany at his birth, Bach's birthday is sometimes cited as March 31 in the Gregorian reckoning, but March 21 remains the date recorded in Eisenach's baptismal register and the one traditionally celebrated.