Брауншвейг-Вольфенбюттель
He was born in Hitzacker, then the residence of his father Duke Augustus the Younger of Brunswick-Lüneburg and his second wife Princess Dorothea of Anhalt-Zerbst. His father assumed the rule in the Principality of Brunswick-Wolfenbüttel, after his Welf cousin Duke Frederick Ulrich had died childless in 1634.