In June 1942, some six months before the American Chicago Pile-1 achieved man-made criticality for the first time anywhere, Döpel's ""Uran-Maschine"" was destroyed by a chemical explosion introduced by oxygen, which finished the work on this topic at Leipzig. Thereafter, despite increased expenditures the Berlin groups and their extern branches didn't succeed in getting a reactor critical until the end of World War II. However, this was realized by the Fermi group in December 1942, so that the German advantage was definitively lost, even with respect to research on energy production.