J. Robert Oppenheimer reveals Emilio Segre's spontaneous fission measurements to the Los Alamos, NM staff. The neutron emission for reactor-produced plutonium is too high for gun assembly to work. The measured rate is 50 fissions/kg-sec, the fission rate in Hanford, WA plutonium is expected to be over 100 times higher still. The discovery of the high spontaneous fission rate of reactor-produced plutonium was a turning point for Los Alamos, NM, the Manhattan Project, and eventually for the practice of large-scale science after the war. The planned plutonium gun had to be abandoned, and J. Robert Oppenheimer was forced to make implosion research a top priority, using all available resources to attack it. A complete reorganization of Los Alamos Laboratory is required. With just 12 months to go before expected weapon delivery a new fundamental technology, explosive wave shaping, has to be invented, made reliable, and an enormous array of engineering problems had to be solved. During this crisis the many foundations for post-war science were laid. Scientist-administrators (as opposed to academic or research scientists) came to the forefront for running large scale research efforts. Automated numerical techniques (as opposed to manual analytical ones) were applied to solve important scientific problems, not just engineering applications. The dispersal of key individuals after the end of the war later carried these insights, as well as the earlier organizational principles developed at Los Alamos throughout American academia and industry.