The German nuclear Energy project, also known as the Uranverein (Uranium Club), began in the spring of 1939 under the auspices of the Reichsforschungsrat (RFR, Reich Research Council) of the Reichserziehungsministerium (REM, Reich Ministry of Education). By 1 September, the Heereswaffenamt (HWA, Army Ordnance Office) squeezed out the RFR and took over the effort. Under the control of the HWA, the Uranverein had its first meeting on 16 September. The meeting was organized by Kurt Diebner, advisor to the HWA, and held in Berlin. The invitees included Walther Bothe, Siegfried Flügge, Hans Geiger, Otto Hahn, Paul Harteck, Gerhard Hoffmann, Josef Mattauch, and Georg Stetter. A second meeting was held soon thereafter and included Klaus Clusius, Robert Döpel, Werner Heisenberg, and Carl Friedrich von Weizsäcker. With Bothe being one of the principals, Wolfgang Gentner, Arnold Flammersfeld, Rudolf Fleischmann, Erwin Fünfer, and Peter Jensen were soon drawn into work for the Uranverein. Their research was published in the Kernphysikalische Forschungsberichte (Research Reports in Nuclear Physics); see below the section Internal Reports. For the Uranverein, Bothe, and up to 6 members from his staff by 1942, worked on the experimental determination of atomic constants, the Energy distribution of fission fragments, and nuclear cross sections. Bothe's erroneous experimental results on the absorption of neutrons in graphite were central in the German decision to favor heavy water as a neutron moderator.