 His father died on 18 July 1605, leaving the duchy under the governance of a regent.In 1608 he began his studies at the age of 14 at the University of Jena accompanied by his younger brothers, Wilhelm and Frederick.While at the university, his guardian appointed a companion and supervisor over the three princes, who later became Field Marshal Kaspar of Teutleben and the Preceptor Frederick Hortleder.