After Enrico Fermi received the Nobel Prize in Physics at the age of 37  in 1938 for his “demonstrations of the existence of new radioactive elements produced by neutron irradiation,” which were later demonstrated to actually be  fission products, he traveled to claim his prize in Stockholm. He used that opportunity to make his exodus from his native country  to escape from Italian dictator Mussolini’s  Italian Racial Laws that affected his Jewish wife Laura. He traveled to New York City along with his family, where they applied for permanent residency.
Upon his arrival in America, he was offered five different chairs at various colleges, and chose to work at Columbia University.
On November 6, 1942 the construction of the world’s first atomic reactor began in the squash court under Stagg Field at the University of Chicago under Fermi’s supervision On December 2, 1942, the pile went critical. This successful experiment was a landmark in the quest for harnessing atomic energy.
Fermi was subsequently detailed by the U.S. Department of War to oversee the production of plutonium at the Hanford Reactor in the state of Washington.
In 1944, Robert Oppenheimer persuaded Fermi to join the Manhattan Project Los Alamos, New Mexico, the U.S. Government’s effort to develop the atomic bomb.
Shortly after he took up residence with his family in Los Alamos, Fermi began making weekly trips, by means of U.S. Army Air Corps Aircraft to San Bernardino, typically on the weekends.. The cover story for these trips was that he was recreating in San Bernardino by visiting with Italian prisoners of war incarcerated at Camp Ono near San Bernardino who had been students of his at the University of Milan in the early 1930s.
Indeed, what Fermi was actually doing was overseeing a crucial part of the atomic bomb making effort, which was taking place in top secret metallurgical facilities in San Bernardino. Tons of uranium ore mined in the San Bernardino Mountains were transported to the facilities, which existed within the Shandin Hills at the north end of the city. Using what was then state-of–the-art equipment, portions of the Shandin Hills had been honeycombed out and lined with lead, and in what was then a remote location,  refinement and enriching of the uranium took place, using a less electricity intensive alternative process than was used at the Oak Ridge, Tennesee facility, creating sufficiently pure Uranium-235, which was then transported back to Los Alamos.
It was a ball of  Uranium-235, together with a smaller ball of plutonium alloyed with gallium, that was wrapped in TNT and then encased in a specially designed, derived and reinforced alloy shell capable of withstanding tremendous force, that made up the first atomic explosive device, the one that was detonated at the White Sands Proving Ground in New Mexico on July 16, 1945. When the TNT inside the shell was detonated it slammed the plutonium into the Uranium 235 with such violence that a critical mass was obtained. Variations of this design, using the same Uranium-235 refined in San Bernardino, were utilized in the “Little Boy” and “Fat Man” bombs dropped on Hiroshima and Nagasaki the following month.
In the more than two  thirds of a century that has elapsed, expansion and development has crept north from San Bernardino and today Shandin Hills is considered an upscale neighborhood in the city of San Bernardino, featuring, among other amenities, a golf course. Most residents of the Shandin Hills district have no idea of the role the scenic hills near their homes played in bringing World War II to a resounding conclusion.