Manhattan Project

J. Robert Oppenheimer, the director at the Los Alamos Laboratory of the Manhattan Project in New Mexico during the 1940s, credited with developing and testing the world's first atomic bomb, spoke to a CBS interviewer in 1965. This eight-minute video shows Oppenheimer's ambivalence about his role in the destruction of Hiroshima and Nagasaki, and the changes nuclear weapons brought about in the world in the 20 years since they had first been used.

Building an atomic bomb is incredibly complex. Creating the first atomic bombs required the joint effort of some of the world’s most celebrated physicists and thousands of workers scattered across the US. This detailed article from the Encyclopedia of the History of Science describes these challenges in great detail, and how those working on the Manhattan Project addressed those challenges.

The brutal 82-day Battle of Okinawa—where US forces suffered nearly 50,000 casualties and Japanese military and civilians lost over 200,000 lives—clinched the grim reality that a full invasion of Japan would be even bloodier. This stark lesson directly shaped American decisions to deploy atomic weapons, aiming to avoid a potentially catastrophic ground war on the Japanese mainland.

A 3-inch, 14-pound sphere of nuclear reactive plutonium-gallium was set to be delivered to the Pacific Theater in 1945 to become the third atomic bomb dropped over Japan. When Japan surrendered, it was returned to Los Alamos in New Mexico for experiment, where two scientists would die testing whether the core could reach criticality—where it would release intense energy—via the use of a dense reflector. Watch the story here.

The National WWII Museum’s “To the Best of My Ability” podcast series delves into how Presidents Franklin D. Roosevelt and Harry S. Truman steered the US through World War Two.

The bombing of Hiroshima and Nagasaki were inarguably devastating, but almost six decades later there is still widespread disagreement regarding how many people were killed by the atomic bombs—both on the day of the bombings and in the months and years that followed. Estimates differ by as many as 100,000 people. This article explores the issue, as well as why people may favor one number over another.

In America, life was transformed by total war: sixteen million service members left civilian life, while massive industrial production demanded labor. Women, minorities, and teens filled factories, fueling boomtown growth and breaking social barriers. Simultaneously, rationing, recycling drives, Victory Gardens, ration stamps, blackout drills, and war bond campaigns permeated daily routines.

One of the perennial moral debates, the dropping of nuclear bombs on Japanese cities prompted strong, polarizing reactions at the time. This article breaks down one side of the argument: that the bomb was designed for defense, using it was illegal and racist, and that there were alternatives.

On August 6, 1945, a bomber named the Enola Gay dropped an atomic bomb on Hiroshima. It was the first time an atomic bomb had been used in combat. The bomb, called Little Boy, destroyed five square miles of the city and killed tens of thousands. This article details the events and offers perspective from both the pilot of the Enola Gay and a Japanese minister who survived the bombing.

The Manhattan Project was a top-secret project during World War II focused specifically on developing the world’s first atomic weapons. This history, created by the National Park Service, provides an excellent overview of the project, which was largely conducted at three sites spread across the US—all now part of the Manhattan Project National Historical Park.