 The death of his father, on the 13 May 1907, made him first in the line of succession to the duchy of Saxe-Altenburg.He inherited the dukedom when his uncle and namesake, Ernst I, died without any surviving male issue.In 1898 in Bückeburg, Ernst married his first wife, Princess Adelaide of Schaumburg-Lippe, a granddaughter of George William, Prince of Schaumburg-Lippe.