The attempt to assassinate Hitler on 20 July 1944 failed in its primary objective, but it did greatly unsettle the Nazi leadership. Some years earlier the Nazis had compiled a list of communist and socialist politicians and activists from the Weimar years who might be rounded up in the event of a deterioration in the domestic political situation. By 1944 the list was somewhat out of date, many of those named on it having already been murdered or died from natural causes, but Jakob and Cilly, whose names were also on the list, were very much alive: overnight on the third weekend in August they were arrested and taken, in the first instance, to Ravensbrück concentration camp. Cilly was subsequently moved to Oranienburg concentration camp and set to work in a munitions factory. According to one source she was then moved again, now to Sachsenhausen concentration camp, in order to avoid the intense aerial bombing of Berlin. A different emphasis comes from another source which states that in April 1945 she was one of a group of concentration camp inmates sent on one of the notorious death marches. She managed to escape back home to Hesse. By early May 1945 : Cilly and Jakob Schäfer now settled back in Marburg which was being administered as part of the US occupation zone.