The Most Terrible Bomb

2 Aug 1939

A letter. In August 1939 Albert Einstein, with help from Leo Szilard, wrote to President Roosevelt. Uranium could make a new kind of bomb, and he believed the German government was backing the research. Roosevelt took over two months to meet the man carrying the letter.

2 Dec 1942

Under the grandstand. In a squash court at the University of Chicago, Enrico Fermi’s team built a pile of black bricks. At 3:25 p.m. on 2 December 1942, Fermi smiled and said “the reaction is self-sustaining.” The news went out by phone, in a code made up on the spot: “the Italian navigator has landed in the New World.”

1943

Three hidden places. In September 1942 the Army put Leslie Groves in command. The bomb was designed at Los Alamos, New Mexico, under J. Robert Oppenheimer. Uranium went to Oak Ridge, Tennessee, where 1,000 families were removed from their homes. Plutonium went to Hanford, Washington, on 400,000 acres.

1944

Borrowed silver. Copper was short, so the electromagnets at Oak Ridge took 14,700 tons of silver borrowed from the U.S. Treasury. Young women ran the machines, many just out of high school. Of the 75,000 people there, the vast majority did not know what the plants were for.

31 May 1945

Without warning. Harry Truman had been President for weeks, and was briefed on the bomb on 25 April 1945. Secretary of War Henry Stimson’s committee met on 31 May. Ernest Lawrence suggested showing Japan a demonstration first. The others feared it might be a dud, or that prisoners of war would be put in the area.

11 Jun 1945

A warning from Chicago. Scientists at the University of Chicago wrote against an “early, unannounced attack.” Show the bomb first, they said, in “an appropriately selected uninhabited area.” Otherwise, they saw what would come next.

16 Jun 1945

No alternative. Five days later the committee’s own scientists answered: Arthur Compton, Lawrence, Oppenheimer and Fermi. They told the committee that their colleagues did not agree with one another. Their own answer was short.

16 Jul 1945

Trinity. Rain pushed the test back to 5:30 a.m. on 16 July 1945. Over the New Mexico desert, Ernest Lawrence saw everything go “from darkness to brilliant sunshine in an instant.” The blast came to 21 kilotons, more than twice what Fermi worked out on the spot from scraps of paper.

17 Jul 1945

A petition. The next day, Leo Szilard’s petition went to the President, signed by seventy other scientists in Chicago. If Japan refused the terms, it allowed, the nation might have to use the bomb. Neither the President nor the Secretary of War saw it before Hiroshima.

25 Jul 1945

Potsdam. A coded telegram told Stimson the results “already exceed expectations.” Truman told Stalin of a new weapon, and Stalin hoped for “good use of it against the Japanese.” In his diary Truman wrote that the target would be “military objectives and soldiers and sailors,” not “women and children.”

Jul 1945

A name on a list. On 25 July Truman gave the order. On 26 July the Allies called on Japan to surrender, in terms that left the emperor’s place unclear. On 29 July Japan rejected them. U.S. intercepts showed Japan seeking a conditional surrender, but American leaders were not inclined to accept one that left its military dictatorship in place.

6 Aug 1945

Hiroshima. At about 8:15 a.m. on 6 August 1945 the Enola Gay released the bomb. It went off 1,900 feet above the city. At 8:16, radio and telegraph contact with Hiroshima ended. Roughly half of those within 1.2 kilometers are estimated to have died that day.

Dec 1945

Who counted. “No one will ever know for certain,” says the U.S. Department of Energy. For Hiroshima alone: 60,000 to 70,000 by the U.S. Bombing Survey in 1946. 78,000 by Allied headquarters. Over 100,000 by the Department of Energy. About 125,000 by the city’s Red Cross Hospital. 140,000, within 10,000, by the city’s museum.

9 Aug 1945

Nagasaki. On 8 August the Soviet Union declared war on Japan. On 9 August, at 11:02 a.m., a second bomb exploded over Nagasaki. The counts differ here too: 39,000 dead by a 1946 U.S. estimate, near 70,000 by the Department of Energy, 73,884 by a city committee in 1949.

15 Aug 1945

The emperor speaks. On the night of 9 August Japan’s leaders split, 3 to 3. The emperor broke the tie: “I cannot endure the thought of letting my people suffer any longer.” Truman halted atomic attacks. He did not like the idea of killing “all those kids,” a member of his cabinet wrote.

1947

The case for. Stimson was told an invasion might cost “over a million casualties, to American forces alone.” At Okinawa, over 12,000 Americans, 100,000 Japanese and perhaps 100,000 Okinawans had died. Many historians argue the bomb ended the war and saved lives on both sides.

1946

The case against. Dwight Eisenhower recalled telling Stimson “that Japan was already defeated.” Admiral William Leahy called it a “barbarous weapon” of “no material assistance.” Other historians argue that Japan would have surrendered anyway, and that the bomb was used to intimidate the Soviet Union.

1997

Still argued. Asked if the bomb was necessary, the historian J. Samuel Walker answered yes and no. This story does not settle it either. Each side’s records are one click away, on every line above.

Jan 1950

The race. The Soviet Union tested its first bomb in August 1949. That December, British intelligence confronted Klaus Fuchs, who had worked at Los Alamos and passed along a sketch of the bomb. He confessed, was convicted of espionage and got 14 years. Four days after his confession, Truman ordered work on the hydrogen bomb.

1954

What they said after. In 1954 the Atomic Energy Commission took away Oppenheimer’s clearance, though its board found “no evidence of disloyalty.” In 2022 the U.S. Department of Energy vacated that decision, calling it a “flawed process.” And Einstein, as Linus Pauling told it, called signing the letter his “one great mistake,” with “some justification.”