After 1918 (mainly for lack of food supplies) he was entered by the Polish authorities on the list of war criminals, which was largely a political and propaganda move (deleted by the Polish side from this list in May 1920 under the influence of the High Commissioner of the League of Nations Reginald Tower and General Commissioner of the Republic of Poland in the Free City of Danzig Maciej Biesiadecki ).

He effectively opposed the plans of transporting General Józef Haller's army to Poland via Danzig, fearing that the Polish side would strengthen its influence in the city.

In his activities, he primarily had in mind the interests of the Free City of Danzig, which he clearly expressed during a speech in Hamburg in October 1927, when he demanded that the authorities of the Weimar Republic conclude a trade treaty with Poland.

He was active in contacts with foreign countries, his trips were aimed at both fostering the growth of trade and emphasizing the distinctiveness of the Free City of Danzig.

In 1921 and 1930 he paid visits to Warsaw, in 1929 to Moscow and Kharkiv, he participated several dozen times in meetings of the League of Nations in Geneva, where he enjoyed the trust of many diplomats.

[2] He became a founding member of Hans Frank's Academy for German Law on 2 October 1933 and joined the Nazi Party in November of that year.

[1] He is buried together with his wife at the Forest Cemetery (Waldfriedhof) in Dahlem (Berlin) (in 1997 transformed into the Garden-Monument (Gartendenkmal)), there is also a plaque commemorating his son Detlef at the grave.

From 1906 he was married to Dorothea (Dora) (23 June 1883 – 8 February 1964), daughter of Heinrich Rolffs (1846–1932), a Pharmacist from Weidenau (North Rhine-Westphalia) and Szczecin, and Adela née Tiemann (1850–1932) .

He had two daughters and two sons: Marianne (1907–1988), whose husband Ulrich-Wilhelm Graf Schwerin von Schwanenfeld (born 1902) was executed in 1944 after the assassination attempt on Adolf Hitler; Gundel, whose husband was a building adviser; Detlef (born 1910), killed in Russia in 1941, and Ulrich (13 October 1917 Bochum – 22 August 2005 Bodenwerder), raised in Gdańsk, doctor of law, arrested in 1944 by the Gestapo after the assassination attempt on Hitler, later a leading West German diplomat, in 1972–1977 ambassador in Moscow, 1977–1979 in Ankara and until his retirement in 1982 in Geneva.

Some of his memories from Gdańsk were published posthumously by the Herder Institute in Marburg (Erinnerungen aus meinen Danziger Jahren 1919-1930, Marburg/ Lahn 1958).