[1] In January 1918 he participated in the strike wave which involved over 400,000 workers across Germany demanding immediate peace without annexation or indemnity, better food, and end to military discipline in the factories and the release of political prisoners.
In January 1919, following the murder of Rosa Luxemburg and Karl Liebknecht the Revolutionary Shop Stewards gathered outside the Trade union Central Headquarters in Hamburg.
In the paper of the KAZ different articles appeared at this time explaining the basis for the decision and why the unions no longer had a raison d’etre for the working class in decadence, and therefore the revolutionary period, of the capitalist system.
During the subsequent months, the tensions and conflicts between the central committee of Paul Levi, and the northern section of the KPD(S) in particular, multiplied, above all around the question of the unions, the AAU and the mass party.
At the Second Congress of the KPD in October 1919 in Heidelberg, where the questions of the utilisation of parliamentarism and the unions were discussed and voted, Appel, as the president and delegate of the Hamburg district, took up a clear position against the opportunist theses which were opposed to the most revolutionary developments.
March 1920 was in fact the period of the Kapp Putsch, during which the central committee of the KPD(S) launched an appeal for a general strike, while propagating a line of ‘loyal opposition’ to the social democratic government and negotiating to avoid any armed revolutionary revolt.
On the basis of Lenin's text "Left-Wing" Communism: An Infantile Disorder, they discussed at great length, refuting among other things the false accusation of syndicalism (in other words the rejection of the role of the party) and of nationalism.
Thus Appel, in his article 'Information on Moscow' and 'Where is Rühle heading?’ in the KAZ, defended the position that Laufenberg and Wolffheim ought to be excluded "since we can have more confidence in the Russian communists than in the German nationalists who have left the terrain of the class struggle".
At the Third Congress of the Communist International, in 1921, Appel again, along with Meyer, Schwab and Reichenbach, were the delegates to conduct the final negotiations in the name of the KAPD, against the growing opportunism of the CI.
They attempted in vain to form a left opposition with the delegations of Bulgaria, Hungary, Luxemburg, Mexico, Spain, Britain, Belgium and the USA.
Firstly, ignoring the sarcasms of the Bolshevik delegation or the KPD, Jan Appel, under the pseudonym of Hempel, underlined at the end of the Third Congress some fundamental questions for the world revolution today.
The Russian comrades have experienced a long Czarist domination, they are hard and solid, whereas where we come from the proletariat is penetrated by parliamentarism and is completely infested by it.
Appel made many other important contributions during the difficult years of the counter-revolution, up until World War II, against the positions of the degenerating Communist Parties, rapidly becoming bourgeois.
That's why Jan Appel was once again present at the end of the sixties at the founding of Revolution Internationale, the future section in France of the ICC, and a product of the massive struggles of the proletariat in 1968.