On 23 March 1925, he was convicted of "participating in high treason" ("Beihilfe zum Hochverrat") and sentenced to a thirty month jail term.

[3][4][a] At or before the start of 1926, initially as an unpaid contributor and then as a contributing editor, he began writing for the Hamburger Volkszeitung, a newspaper founded in 1918 which since 1920, had operated as a Communist Party publication.

During summer 1931, he became a course leader and teacher at the "Rosa Luxemburg" state party academy which had recently relocated to Fichtenau (Schöneiche), just outside Berlin.

Tried and convicted on 8 June 1932 under a charge of preparing to commit high treason ("Vorbereitung zum Hochverrat"), he was sentenced to a two year jail term.

During 1933, in the aftermath of the take-over of the party's Berlin headquarters at the "Karl Liebknecht Haus" by Nazi paramilitaries on 8 March 1933, Rembte met on a number of occasions with Hermann Schubert.

Under the cover name "Rudolf", Rembte was based in Merseberg as principal advisor to the (illegal) regional party leadership between June and (probably) November 1933.

[3][4][5] Towards the end of 1933, a wave of arrests by the security services suggested that the local party branch had been penetrated by police spies, driving Rembte to leave the Halle region.

A relatively strong and well-organised local Communist party branch had survived there, despite the need to operate "illegally and underground" in conditions of tight secrecy.

[5] Rembte arrived in December 1934 and remained in the Lower Rhine region for approximately five months, using alternately the cover names "Poser" and "Oskar".

In Prague, he conducted daily meetings with Robert Stamm and Herbert Wehner, making arrangements for a new Berlin regional leadership organisation.

It is a mark of the importance the party attached to these preparations that the meetings also involved Walter Ulbricht and Franz Dahlem, both of whom were at this stage living in exile in Paris, and both of whom emerged after 1949 as prominent communist leaders (and mutually mistrustful political rivals) in the Soviet sponsored German Democratic Republic (East Germany).

On 4 June 1937, Rembte, together with comrades Walter Griesbach and Käthe Lübeck, appeared before the special "People's Court", facing a charge of preparing a highly treasonable undertaking ("Vorbereitung eines hochverräterischen Unternehmens").

He died as an inmate of the Brandenburg-Görden Prison on 22 October 1943 because of a serious stomach illness in respect of which, according to sympathetic sources, he was not provided with the necessary medical attention.

International condemnation from countries in which, hitherto, many of the more negative manifestation of Hitler's new Germany had received little press coverage, intensified after the executions.