was awarded the Order of St Hubert by the Bavarian King and received the Order of the Black Eagle from the Prussian King when he travelled to Berlin. Ernst hardly made any political appearances, loved hunting, but was very open-minded about the country's social problems. He simplified the state administration and Altenburg developed into an important industrial town under his rule. In 1864 he had the town hall in Altenburg restored, in 1871 the court theatre was opened and five years later the state museum. On 29 April 1873, the ownership structure of the ducal house and the state was reorganised in a Domain Fideicommiss. During a trip to St. Petersburg in 1873, he received the ownership of the 50th Infantry Regiment "Bialystok" from Tsar Alexander II. The Duke subsequently also travelled to Turkey and Austria-Hungary. On 9 February 1855, Ernst passed a military law that established the close connection to Prussia. A week later, he was appointed Prussian major general à la suite and four years later lieutenant general. On 30 March 1862, he concluded a military convention with Berlin and a year later no longer took part in the Frankfurt Diet. At the outbreak of the German War between Prussia and Austria, he concluded a military alliance with Prussia on 21 June 1866, despite the sympathies of many Wettiners for Austria. Among other things, he recognised the draft for the new federal order drawn up by Prussia and in return received a guarantee for the independence and integrity of his territory. However, the required Altenburg contingent was not involved in any military action. In 1866, Saxony-Altenburg joined the North German Confederation and the military system was reformed along Prussian lines. Following the Federal Council's decision to mobilise the army for the war against France on 15 July 1870, Duke Ernst travelled to Berlin two days later to declare his allegiance to Wilhelm I. He was given permission to join the staff of the German Confederation. He took part in the siege of Paris and the battles on the Loire, among other things. He also took part in the imperial proclamation in Versailles on 18 January 1871. On 28 September 1907, Wilhelm II appointed him colonel general with the rank of field marshal. He was also Saxon Colonel General and head of the Jäger Battalions No. 6 and 12. In 1873, the Duke married his only daughter to the Prussian Prince Albrecht. In 1891, he had a monument erected in Altenburg to Emperor Wilhelm I, whom Ernst so admired. After an unusually long reign of 55 years, his nephew Ernst II of Saxe-Altenburg took over the regency after his death in 1908. Duke Ernst I was considered a close friend of all three German emperors.