During the reign of Archbishop Schrattenbach the Mozarts had enjoyed recognition, generosity and status (father Leopold was appointed Deputy Kapellmeister).
That all changed in 1772 when Schrattenbach’s successor, Archbishop Colloredo, took the reins. In order to make the church service more intelligible to the general congregation he removed any purely instrumental music, put a strict limit on the length of settings of the mass and instituted hymns to be sung in German. What with other reforms in Salzburg’s musical institutions, the Mozarts found their status compromised. Indeed, Leopold had been expecting promotion to the position of Kapellmeister, but Colloredo preferred Italian musicians.
Leopold found he had a new Kapellmeister, one Domenico Fischietti. They do not seem to have hit it off, and there was clear mutual dislike between Colloredo and the Mozarts.
In 1776 it was hoped Wolfgang would get the job of organist at Trinity Church. Their friend Michael Haydn (Josef’s younger brother) was appointed instead. The friendship ended suddenly amidst great acrimony.
Finally in 1777 Mozart wrote a petition to the Archbishop asking to be released from his employment. Archbishop Colloredo dismissed him, and his father too.