ALBUQUERQUE, N.M. — Transported in the backseat of a blacked-out Plymouth sedan was the culmination of years of feverish work — a hefty plutonium core that would soon be used to trigger the world’s ...

At 5:30 a.m. mountain war time on July 16, 1945, the world’s first nuclear weapon detonated over a flat, arid stretch of New Mexico desert. The Trinity test, as it was code-named, confirmed that an ...