On May 19, 1945, eleven days after the surrender of Nazi Germany in Europe, a U-boat was escorted into Portsmouth Naval Yard, New Hampshire. News reporters covering the surrender of U-234 were ordered, contrary to all previous and later U-boat surrender procedures, to keep their distance from crew members and passengers of U-234, on threat of being shot by the attending Marine guards. Why the tight security? Buried in the nose of the specially-built mammoth boat, sealed in cylinders "lined with gold," was 1,120 pounds of enriched uranium labeled "U235"the fissile material from which atom bombs are made. Critical Mass documents how these Nazi bomb components were then used by the Manhattan Project to complete both the uranium bomb dropped on Hiroshima and the plutonium bomb dropped on Nagasaki, to defeat the Japanese and win World War Two and global domination in the modern age.