[1] Raumer married Stephanie (1882-1949, daughter of Stephan Gans zu Putlitz [de]) at Belgrad in 1905.
He left public service in 1911 and became director of Hannoversche Kolonisations- und Moorverwertungsgesellschaft, an electricity plant at Osnabrück.
From 1915 he was director of the Bund der Elektrizitätsversorgungs-Unternehmungen Deutschlands (the association of German power-generating utilities) at Berlin.
To this end he invited representatives of industry (Siemens, Rathenau, Felix Deutsch [de], Anton von Rieppel [de]) and of the unions (Carl Legien, Gustav Bauer, August Schlieke, Theodor Leipart) to a meeting in October 1918.
This resulted, one month later, in the creation of the Zentralarbeitsgemeinschaft [de] (ZAG), which established the formal equality of employers and employees and fixed the length of the working day at eight hours.
He focused on the question of war reparations - into his tenure fell the Spa Conference of July 1920, the interruption of negotiations by the Allies in January 1921 and the occupation of Duisburg and Düsseldorf in March 1921.
Having established contacts to the Soviet negotiators Karl Radek and Georgy Chicherin there, he subsequently pushed Rathenau to agree to the Treaty of Rapallo.
[1] Raumer was a friend of the French ambassador André François-Poncet and supported Heinrich Brüning's policy of economic rappraochment with France.