Sender's return journey to Germany happened during the mass mobilisation of the
First World War. Although she travelled back via
Switzerland, she was only able to make her way back to Biebrich thanks to help from soldiers on their way to the front. Her family doctor invited her to join the staff at a local hospital and help treat the wounded. However she soon concluded that her principal role was to patch up wounded soldiers so that they could be sent back to the front as soon as possible. So when she was invited to work in Frankfurt for the metal company which had previously employed her before the war, she readily accepted – although this too involved war-work, as did virtually all jobs in war-time Germany. Nevertheless, her work made her aware of many secrets which would have been valuable to the anti-war movement. Sender decided to compartmentalise her life, seeing it as a matter of honour not to disclose secrets discovered at work to her political colleagues. When the SPD voted for war credits, Sender considered leaving the party. She then heard that an anti-war opposition group had formed within the party and that
Robert Dissmann was the local organiser. Dissmann was an official with the
German Metal Workers' Union. Sender met Dissmann in the summer of 1916. Dissmann had just been meeting with
Rosa Luxemburg shortly before she was imprisoned. Dissmann soon recruited her to join the anti-war faction within the SPD. When Max Quarck, the sitting SPD member of the Reichstag, addressed a meeting in favour of the war credits, Sender spoke against him. However such opportunities for debate became rarer as the majority disregarded the rights of the minority. Dissman decided to set up the anti-war minority through establishing a local section of the National Federation of Proletarian Thinkers as a
front organisation. He asked Sender to take on the role of organising it. Their attempts to disguise their political purpose were often ineffective and they were subject to police surveillance. Often, they had meeting venues cancel their bookings. Sender claimed that the military authorities also took an interest in them, resulting in many of their members being called up for the army. She attended the
Third International Socialist Women's Conference held at
Bern March 26–28, 1915, where she encountered
Lenin's manipulation of the Bolshevik Women's delegation and took a dislike to
Karl Radek who was acting as Lenin's aid. == German Revolution and Weimar Republic ==