In 1918 Heartfield joined the Berlin Dada Club and the German Communist Party. He was dismissed from the military film service on account of his support for a strike following the assassination of Karl Liebknecht and Rosa Luxemburg. With George Grosz he was then to found Die Pleite, a satirical magazine.
He met Bertolt Brecht in 1924. Brecht was to have a profound effect on his artistic and intellectual development. Heartfield became progressively more engaged in photomontage as a form of political and artistic representation in the following years.