Encouraged by Leo Szilard and galvanized by German success in achieving nuclear fission, the United States embarks on a crash program to build a nuclear bomb. Aided by many Jewish scientists who had fled Nazi Germany the project team successfully constructs three fuel production lines using different technologies and assembles three bombs. One bomb was tested in New Mexico and the others deployed against the Japanese cities of Hiroshima and Nagasaki.

Siege machines convert energy into mechanical force to breach barriers.