 Until the Napoleonic Wars, Blankenhain had been a part of the Duchy of Saxe-Weimar.After the Fourth Coalition's defeat at Jena and Auerstedt, Napoleon attached the Lordship of Blankenhain to the Principality of Erfurt, directly subordinate to himself as an "imperial state domain" (), separate from the Confederation of the Rhine (nominally a French protectorate set up to replace the now-defunct Holy Roman Empire), which the surrounding Thuringian states had joined.After the Congress of Vienna, Erfurt was restored to Prussia on 21 June 1815, becoming the capital of one of the three districts (") of the new Province of Saxony, but some southern and eastern parts of Erfurter lands joined Blankenhain in being transferred to the newly promoted Grand Duchy of Saxe-Weimar-Eisenach the following September.