His proficiency on the organ was unequaled in Europe - in fact, he toured regularly as a solo virtuoso - and his growing mastery of compositional forms, like the fugue and the canon, was already attracting interest from the musical establishment - which, in his day, was the Lutheran church. But, like many individuals of uncommon talent, he was never very good at playing the political game, and therefore suffered periodic setbacks in his career. He was passed over for a major position - which was Kapellmeister (Chorus Master) of Weimar - in 1716; partly in reaction to this snub, he left Weimar the following year to take a job as court conductor in Anhalt-Cothen. There, he slowed his output of church cantatas, and instead concentrated on instrumental music - the Cothen period produced, among other masterpieces, the Brandenburg Concerti.
While at Cothen, Bach's wife, Maria Barbara, died. Bach remarried soon after - to Anna Magdalena - and forged ahead with his work. He also forged ahead in the child-rearing department, producing 13 children with his new wife - six of whom survived childhood - to add to the four children he had raised with Maria Barbara. Several of these children would become fine composers in their own right - particularly three sons: Wilhelm Friedmann, Carl Philipp Emanuel and Johann Christian. After conducting and composing for the court orchestra at Cothen for seven years, Bach was offered the highly prestigious post of cantor (music director) of St. Thomas' Church in Leipzig - after it had been turned down by two other composers. The job was a demanding one; he had to compose cantatas for the St. Thomas and St. Nicholas churches, conduct the choirs, oversee the musical activities of numerous municipal churches, and teach Latin in the St. Thomas choir school. Accordingly, he had to get along with the Leipzig church authorities, which proved rocky going. But he persisted, polishing the musical component of church services in Leipzig and continuing to write music of various kinds with a level of craft and emotional profundity that was his alone.
Bach remained at his post in Leipzig until his death in 1750. He was creatively active until the very end, even after cataract problems virtually blinded him in 1740. His last musical composition, a chorale prelude entitled "Before They Throne, My God, I Stand", was dictated to his son-in-law only days before his death. .