Pre - Discovery 

In 1932 the neutron(a particle without a charge) was discovered. In 1934 Fermi bombarded a Uranium nucleus with neutrons. Fermi did not find anything that stood out and most people did not question it.

Lise Meitner met Otto Hahn in Berlin, and they began working together.  Meitner and Hahn realized that Fermi had not considered all the possibilities and decided to preform an experiment of their own.

Meitner and Hahn teamed up with Fritz Strassmann who was a renowned chemist. They set up an experiment with three rooms: the Irradiation room, Chemistry lab, and measuring room. They then proceeded to bombard Uranium nucleus's with neutrons. 

Meitner was forced to flee the Nazi's. After Meitner left Hahn and Strassmann continued the experiments. Hahn maintained a long-distance correspondence with Meitner, telling her about their continued studies.