Desperately in need of funds, he resorted to the practice of arresting wealthy subjects without cause, and setting them free only after they had renounced their fortunes to the duke, or had paid exorbitant ransoms.

The duke maintained a standing "harem," in which two noble "Ladies of Honour" (Ehrenfräulein) and three "Chamber Women" (Kammerfrauen) of low birth attended to his desires.

They had eight children: After the death of his first wife in 1726, the duke decided to not marry again, choosing to live quietly with his Ladies of Honor and Chamber Women.

One of the duke's few wise decisions was the institution of primogeniture in Saxe-Weimar (confirmed in 1724 by the Emperor Karl VI); this stopped further land divisions in the future.

The annexation of Saxe-Eisenach was favorable to the hunt-loving duke; he possessed a large swath of woods in the Eisenach region, which seemed suitable to him for hunting.

The gesture demonstrated that the citizens of the duchy were resisting the introduction of absolutism, thus certain policies that Ernst August had planned could not be completely carried out.