Duke Maurice had received the secundogeniture of Saxe-Zeitz from the hands of his father, Elector John George I of Saxony in 1652 and had Moritzburg Castle erected as his residence.

It was due to his published defense of this marriage that philosopher Christian Thomasius was forced to leave the strongly Lutheran Leipzig to settle in Halle, where he was involved in the creation of the university there, under the patronage of Frederick William.

Moritz Wilhelm tried to reach the acknowledgement of his Saxe-Zeitz lands as a sovereign Imperial State, referring to the princely Hochstift rights of the former Bishops of Naumburg-Zeitz; however, his attempts failed due to the veto of the Saxon electors.

After Moritz Wilhelm's only son and heir, Frederick August, died in 1710 at the age of nine, the duke finally reconciled with the Saxon electors and waived all claims to Imperial immediacy.

Shortly before his death in 1717, the duke converted from Calvinism to Catholicism in order to please his brother Christian August, who was a Prince of that Church as Archbishop of Esztergom and Primate of Hungary.