Mewis also briefly served as Chairman of the State Planning Commission before having to step down due to the supply crisis in the GDR.

From 1925 to 1928, he was the chairman of the Hessen-Waldeck branch of the Communist Youth League,[1] and from 1929 to 1932, he was the organizational secretary of the KPD District Directorate in Magdeburg-Anhalt.

[2] From 1932 to 1934, Mewis attended the International Lenin School in Moscow, after which he worked illegally for the KPD as the Political Leader of the Wasserkante Party District (consisting of Hamburg and Schleswig-Holstein) until 1936.

He was tasked with establishing a new leadership of the KPD in Sweden, along with Herbert Wehner and Heinrich Wiatrek, to coordinate illegal activities in the German Reich territory.

Party Congress), he was a candidate member of the Politburo of the Central Committee of the SED,[2][3] the de facto highest leadership body in East Germany, the Bezirk Rostock being strategically important because of its maritime border.

[2] In July 1961, the Central Committee of the SED voted to remove State Planning Commission Chairman Bruno Leuschner.

His leadership was additionally strained by bad relationships with his colleagues in COMECON, especially the Polish, who complained about his arrogance and lack of knowledge.

[3] In January 1963, Mewis was relieved of all his duties due to the so-called supply crisis in the GDR (1962/63) and replaced by economics expert Erich Apel.

[2] As part of his research for the novel "The Aesthetics of Resistance," Peter Weiss conducted a lengthy interview with Karl Mewis about his time in emigration.

In 1939, he married Luise (known as Liesel), the daughter of the communist politician Franz Dahlem, who lived with him in Stockholm (*1919, divorced in 1953, died in 1957).

When his mentor Franz Dahlem was deposed under the pretext of having relationships with Noel Field, who was denounced as an American spy, Mewis did not participate in the campaign against him, but he also did not defend him.

Both marriages produced children, including Liesel Catherine (*1941, married Haacke, Africanist with a doctorate), Franz (longtime opera singer in Rostock), and Annette (Ph.D. in media studies).