Sixty-six years ago, at the end of July and early August, US policymakers and President Truman made fateful decisions that meant the use of two atomic bombs against Japanese cities was almost inevitable—virtually unstoppable. Then film footage and other evidence of the true effects of the bomb were suppressed for decades. We’ve been living with the nuclear after-effects ever since, from Hiroshima to Fukushima.

Starting July 25, and related to publication of my new book and e-book Atomic Cover-up, on that film’s suppression, I began offering a daily record of what transpired leading up the bombing of Hiroshima and Nagasaki in 1945. (For more, including video, see my personal blog and major new article at Japan Focus.)

On this day in 1945:

—Early today, Paul Tibbets, pilot of the lead plane, the Enola Gay (named after his mom) on the first mission, reported to Gen. Curtis LeMay’s Air Force headquartters on Guam. LeMay told him the “primary” was still Hiroshima. Bombardier Thomas Ferebee pointed on a map what the aiming point for the bomb would be—a distinctive T-shaped bride in the center of the city. “It’s the most perfect aiming I’ve seen in the whole damned war,” Tibbets said. But the main idea was to set the bomb off over the center of the city, which rests in kind of a bowl, so that the surrounding hills would supply a “focusing effect” that would lead to added destruction and loss of life.

—By 3 pm, top secret orders were being circulated for Special Bombing Mission #13, now set for August 6, when the weather would clear. The first alternate to Hiroshima was Kokura. The second, Nagasaki. The order called for only “visual bombing,” not radar, so the weather had to be okay. Six planes would take part. Two would escort the Enola Gay, one would take photos, the other would be a kind of mobile lab, dropping canisters to send back scientific information.

—Meanwhile, three B-29s arrived at Tinian carrying from Los Alamos the bomb assemblies for the Fat Man device (which would use plutonium, the substance of choice for the future, unlike the uranium bomb meant for Hiroshima).

—President Truman finally left the Potsdam conference in Germany and set sail for home, having approved the message he would deliver if and when the first use of the bomb against the Japanese proved to be a success, likely before he reached America.

—Japanese cables and other message intercepted by the United States showed that they were still interesting in enlisting the Soviet’s help in presenting peace terms but were undecided on just what to propose. The Russians, meanwhile, were just five days from declaring war on Japan.

—Six years ago earlier on this day, August 2, 1939, Albert Einstein sent a letter to President Roosevelt stating the Germans were trying to enrich uranium 235—and that this process would allow them to build an atomic bomb. This helped spark FDR’s decision to create the Manhattan Project.

Greg Mitchell’s new book (also out as an e-book) is Atomic Cover-Up: Two US Soldiers, Hiroshima & Nagasaki, and The Greatest Movie Never Made. He also co-authored, with Robert Jay Lifton, Hiroshima in America.