On 20 July 1944 an assassination attempt was made against Adolf Hitler. The dictator survived, but the leadership were badly unnerved: the régime had already prepared a list of several thousand names of political adversaries, many of them surviving former left wing politicians from the Weimar era, to be used in the event of an escalation in political tension on the home front. The name of Johanna Tesch was on it. She was arrested on 22 August 1944 and taken to the concentration camp at Ravensbrück. By this time her second son, Wilhelm Tesch, had already been killed in the war. Fellow inmates recalled that from the concentration camp she was permitted to write to her family regularly, using her letters, which were naturally subject to SS censorship, to reassure them that she was well. Nevertheless, she had been suffering from serious heart and kidney illness at the time of her arrest and her husband had been struggling, without success, to obtain her release on grounds of her poor health. Roughly 6 months later, on 10 March 1945, fellow inmates got hold of a pen and paper for her, and Johanna Tensch started to write her fare-well letter. Three days later she died, probably from a combination of the medical conditions from which she had been suffering at the time of her arrest and the malnutrition which was endemic in the concentration camp.