In the course of the war, Prussian troops had occupied the Free City of Frankfurt and the King of Prussia (later to become the German Kaiser, or Emperor) had purchased the remnants of the Thurn-und-Taxis Post organisation.
According to article 48, the federal area of the Northern German states, de facto an enlarged Prussia, came under the united postal authority, led by director Heinrich von Stephan.
On 1st January 1876 a Reichspostamt under Postmaster General von Stephan was split-off from Bismarck's Reich Chancellery as a government agency in its own right.
The postal area was significantly enlarged with the incorporation of the Saar territory in 1935, the Austrian Anschluss in 1938, and the annexation of the Sudetenland according to the Munich Agreement.
The last Reichspostminister Julius Dorpmüller, a member of the Flensburg Government, was arrested two weeks later, and governmental authority was officially taken over by the Allied Control Council with the Berlin Declaration of 5th June.