During the middle 1930s he spent time in the Hohnstein Concentration Camp, but he was released and participated in the Spanish Civil War on the anti-fascist side.

[3] He applied for and obtained a special dispensation from the regional Ministry of Economics to enroll at the Technische Hochschule Dresden) despite never having completed his school exams.

[1] In 1928 he had joined the Young Socialists, and in 1929 became a member of the Social Democratic Party ("Sozialdemokratische Partei Deutschlands" / SPD).

The German-Jewish Hiker League was dissolved in Easter 1932 as a consequence of increasing tensions between right-wing nationalists and socialist member.

Later that year Blackstein joined the "Free German-Jewish Youth" ("Freie Deutsch-Jüdischen Jugend") group, which was concerning itself with educating Jewish youngsters on the merits of socialist approaches and attitudes.

Those excluded responded by setting up the Socialist Workers' Party ("Sozialistische Arbeiterpartei Deutschlands" / SAPD).

[1] He was also entrusted with what was termed, in the spirit of the time, Agitprop work in the Dresden area, and it was in this context that he set up a political cabaret group called "Die Nebelspalter" (loosely "The fog destroyers") which campaigned for the SAPD in the two general elections of 1932.

Although the focus of his journalistic work remained on the arts, he was also writing in support of the fight against the introduction of military sports ("Wehrsport") and of voluntary labour service ("Freiwilliger Arbeitsdienst") which the government was promoting as a remedy against the very high levels of unemployment which accompanied the economic depression that had been triggered by the Wall Street Crash back in 1929.

[3] Later he would use his experience from the inside of the Nazi prison system in a theater play "Ein Prozeß" ("A trial"), published and first performed in Oslo in 1938.

[3] Blachstein was at an increased risk of arrest as long as he remained in Germany because his Jewish provenance was a matter of public record.

He remained in contact with the SAPD leadership, from whom he received an instruction, in July 1935, to relocate again, this time travelling via Gdingen and Copenhagen to Oslo, Norway.

The Oslo affiliate was led by Willy Brandt, with whom Peter Blachstein was able to build a relationship of mutual trust.

He was also entrusted with organising and implementing a theoretical training programme for the IBRJ, designed to help create a united front against fascism.

[1] In the summer of 1936 Blachstein travelled to Paris, by now a principal centre for exiled left-wing German politicians.

In June 1937 Blachstein was arrested in Barcelona by communist secret police and accused of spying for Franco and working for the Gestapo.

Because of the appalling hygiene he soon fell ill with Tuberculosis, as a result of which he was transferred to a sanatorium controlled by anarchist comrades.

That was absent from the Soviet labour camps which lacked the cruelty and deathly fury that characterised the SS-camps where the very purpose of the place was destruction and extermination Es ist nicht Vernichtung durch Arbeit, was das Kennwort des KZ-Systems war, sondern ‚Arbeit ohne Rücksicht auf Vernichtung'.

After a period recovering from an operation in connection with his Tuberculosis, he started working in the secretariat of the International Labour Front Against War which had been jointly created in September 1938 by the (Dutch) Revolutionary Socialist Party, the (British) Independent Labour Party, the (Spanish) POUM and the (exiled German) "Neuer Weg" group.

In his Swedish exile he found time to refresh his college studies, revisiting topics in Economics, History and Literature.

Working with an Uppsala University student theatre group he was deeply involved in the translation and production of several plays by Bertolt Brecht.

Blachstein remained in Sweden until the early summer of 1947, working in Stockholm as secretary to the International Rescue and Relief Committee (IRRC).

When he returned to occupied Germany on 6 or 27 May 1947[10] he settled not in Dresden but in Hamburg, at that time administered as part of the British occupation zone.

In the western occupation zones a return to a multi-party political structure was being implemented, and Blachstein joined the Social Democratic Party ("Sozialdemokratische Partei Deutschlands" / SPD), while supporting himself successfully as a free-lance journalist.

[1] After a period of recuperation his health improved, and between 1970 and 1972 he found himself working directly for Willy Brandt, employed as an officer of the Government Press Service.

Blachstein himself was a committed atheist who could never understand how a national government could simply decide who was Jewish and who was not: he robustly rejected the conflation of race and religion.