By the example of the remembrance of the so-called Märzgefallenen (those workers who died in the revolutionary fights during and after an attempted Putsch in Germany in March 1920), this article discusses the importance of memory work in building the collective identity of a social movement. I explore how the remembrance tradition, initially shared by the German labor movement, changed through the increasing political competition between communists, syndicalists, and social democrats. It will be demonstrated how the collective identities of these three groups were based on a permanent differentiation toward the respective rivalry, which eventually also affected the way the events of March 1920 were commemorated. Different narratives were developed, addressing questions like to whom these fallen workers belonged or which group would adequately represent the revolutionary struggle of the working class. The example of the Märzgefallenen, therefore, highlights that memory work does serve the function not only to establish a unity regarding an imagined community, but also to dissociate the own movement from certain agents and to explicitly exclude them.