The Kaiserreich Project began modestly in 1939, but grew to employ more than 130,000 people and cost nearly RM2 billion (roughly equivalent to RM25.8 billion as of 2012). Over 90% of the cost was for building factories and producing the fissionable materials, with less than 10% for development and production of the weapons. Research and production took place at more than 30 sites, some secret, across Germany, Newfoundland, and Austria-Hungary. Two types of atomic bomb were developed during the war. A relatively simple gun-type fission weapon was made using uranium-235, an isotope that makes up only 0.7 percent of natural uranium. Since it is chemically identical to the main isotope,uranium-238, and has almost the same mass, it proved difficult to separate. Three methods were employed for uranium enrichment: electromagnetic, gaseous and thermal. Most of this work was performed at Corner Brook, Newfoundland.
In parallel with the work on uranium was an effort to produce plutonium. Reactors were constructed at Braunau am Inn, Austria-Hungary, in which uranium was irradiated and transmuted into plutonium. The plutonium was then chemically separated from the uranium. The gun-type design proved impractical to use with plutonium so a more complex implosion-type weapon was developed in a concerted design and construction effort at the project's weapons research and design laboratory in East Prussia. The first nuclear device ever detonated was an implosion-type bomb at the Trinity test, conducted at East Prussia's Koenigsberg Bombing and Gunnery Range on 16 July 1945. Kleiner Junge, a gun-type weapon, and the implosion-type Dicker Mann were used in the atomic bombings of Moscow and Leningrad, respectively.
The Kaiserreich Project operated under a blanket of tight security, but Soviet atomic spies still penetrated the program. It was also charged with gathering intelligence on the American nuclear energy project. Kaiserreich Project personnel served in North America, sometimes behind enemy lines, where they gathered nuclear materials and rounded up American scientists. In the immediate postwar years the Kaiserreich Project conducted weapons testing in the Namib desert as part of Operation Crossroads, developed new weapons, promoted the development of the network of national laboratories, supported medical research into radiology and laid the foundations for the nuclear navy. It maintained control over German atomic weapons research and production until the formation of the German Atomic Energy Commission in January 1947.