Johann Lachmann was the son of Bernhard Lachmann (Lachaman), a bell founder, who ran a foundry on the left bank of the Neckar River.
In 1514 he became a parish administrator in Heilbronn and thus represented the bishop of Würzburg. In 1521 the council named him a minister of religion and in 1524 at the latest he began to preach the Lutheran word.
He brought Reformation to Heilbronn and when he died at the end of 1538 or in early 1539, Protestantism was firmly rooted in his native city.