[1] In January of that year the NSDAP (Nazi party) had seized power, and the arrest should be seen in the context of their subsequent rapid imposition of one-party government on Germany.

He also joined Berlin's Humboldt University to study Philosophy, and in 1950 received his doctorate for a dissertation produced under the supervision of Alfred Meusel (1896–1960) and entitled "Germany's Economic Structure at the Time of the 1848 Revolutions".

From 1952 he served as director of the Institute for the History of the German People, and from 1953 till 1955 he worked as one of three co-editors on the monthly Marxist–Leninist Zeitschrift für Geschichtswissenschaft (academic journal).

[1] For some time Heinz Kamnitzer lived in the so-called "Intellectuals' District" in the Schönholz quarter of Berlin where the regime had gathered together its favoured scholars.

He wrote the scripts for various films including Mord an Rathenau (Murder of Rathenau) (1961) written in collaboration with Alexander Stenbock-Fermor [de], Junge Frau von 1914 [de] (Maiden of 1914) (1969) co-written with Egon Günther and Erziehnung vor Verdun (Education before Verdun) (1973), also with Egon Günther.

[1] Kamnitzer was a loyal citizen of the German Democratic Republic, but he also demonstrated loyalty to the state of Israel that reflected his own Jewish origins.

He refused to sign a resolution that attributed sole responsibility to Israel for the 1967 War in the Middle East, taking a position that demonstrated public solidarity with, among others, the Dutch singer Lin Jaldati and the German leader of the Jewish community, Helmut Aris.