Manhattan Project unlocked the atom

NASHVILLE — It was a project so secret that Vice President Harry Truman didn’t even learn about it until he was sworn into office after Franklin Roosevelt’s death.

The Manhattan Project was responsible for building and deploying the world’s first atomic bombs. In August 1945, two bombs developed by the project’s scientists were dropped on Japanese cities, leading to Japan’s surrender and ending the war.

Roosevelt approved the project in December 1942 after Albert Einstein and other scientists warned that the Nazis were likely working on a nuclear weapon.

In a rural strip of east Tennessee, a secret city was born almost overnight, with 30,000 workers brought in to build a plutonium plant and an enriched uranium plant to make the fuel that would ultimately power the bombs. The enriched uranium produced at that secret city, now known as Oak Ridge, was shipped to Los Alamos, New Mexico, for use in atomic bombs.

It fell to Truman to authorize the first — and only — wartime use of nuclear weapons.

“The irony was that Truman had to make the decision — Truman, who actually dropped the bomb, knew not a single thing about its development,” says Amy Sayward, professor of history at Middle Tennessee State University in Murfreesboro. “It was an awesome responsibility.”

The legacy of the Manhattan Project remains mixed, Sayward says. The bombs dropped in Japan killed more than 129,000 people — most of them civilians. And they spawned a global sense of insecurity about the ability of bad actors to develop and deploy nuclear weapons, a fear that lingers today.

But the project also effectively ended World War II. Japan surrendered within two weeks of the detonations of bombs developed by the Manhattan Project.

Wadhwani also reports for The Tennessean of Nashville.