In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.

The duchy was split up again after Ernest ’ s death in 1675 , and the Duchy of Saxe-Gotha-Altenburg officially came into existence in 1680 when his eldest son , Frederick , took control of the parts of the country Gotha and Altenburg .
It was common for the Ernestine duchies to merge and split ; Ernest 's combined duchy was divided again after his death in 1675 , and the Duchy of Saxe-Gotha-Altenburg proper came into existence in 1680 with the completion of this division and the accession of his eldest son , Frederick to the subdivision centered on the towns of Gotha and Altenburg .