[1] He was born in Oranjewoud, the eldest and only surviving son of Johann Wilhelm, Duke of Saxe-Eisenach and his first wife Amalie of Nassau-Dietz.

He married his second wife Anna Sophie Charlotte of Brandenburg-Schwedt in Berlin on 3 June 1723, just eight months after the death of Albertine Juliane.

From 1730 to 1741, Johann Adam Birkenstock served the director of music and the leader of the court orchestra, a position referred to as the Kapellmeister.

[2] Wilhelm Heinrich acceded to the duchy of Saxe-Eisenach in 1729 upon the death of his father and was succeeded by his second cousin, duke Ernst August I of Saxe-Weimar.

As early as 1723, through his marriage to a Prussian princess, knight of the Order of the Black Eagle, he showed great interest in everything military.