By Jonny Lupsha, News Writer

Seventy-five years later, the Hiroshima bombing still raises controversy, NPR reported. The nuclear bombing of two sites in Japan—Hiroshima and Nagasaki—by the United States ended World War II, though the death toll remains unknown. The Great Courses remembers this historic event.

According to the NPR article, “Some prominent experts in the law of war are also reexamining the Hiroshima attack,” which was the first and only use of atomic weaponry during wartime, carried out by the United States, including the atomic bombing of Nagasaki three days later. “At the time, the morality and legality of those nuclear attacks were hardly the subject of public debate,” the article said. The article also quoted U.S. President Harry Truman’s speech hours after the bombing, in which he said, “Let there be no mistake; we shall completely destroy Japan’s power to make war” and that if Japan didn’t accept the terms of surrender, Japan should expect quite a bit more of the same.

In the subsequent years since the attacks, as more survivors of the blasts have told their stories, and as international humanitarian law has changed, the morality and legality of the Hiroshima and Nagasaki killings have indeed come under scrutiny.

Regardless of opinion, the day of the bombing of Hiroshima—August 6, 1945—remains one of the most historically significant dates of humanity. While it brought about the events that led up to the end of World War II, it was the first time in history that an atomic bomb was deployed. Here is what led up to the bombing.

The Potsdam Declaration

In Potsdam, Germany, President Harry Truman pushed for an unconditional surrender by Japan in what became known as “The Potsdam Declaration,” which was signed by the United States, Great Britain, and China.

“That Potsdam Declaration demanded of the Japanese that they put an end first to Japanese militarism; that there would be a punishment of Japanese war criminals; there would be a military occupation of Japan; the Japanese would have to evacuate all occupied territories; and would have to agree to complete disarmament,” said Dr. Thomas Childers, Sheldon and Lucy Hackney Professor of History at the University of Pennsylvania.

“The Allies, on the other hand, promised to establish a democratic government in Japan; to help rebuild Japanese industry destroyed in the massive American air raids on Japan; and to end the military occupation of Japan when it was clear that the Japanese had established a ‘peacefully inclined and responsible government.’”

The Japanese response to the Potsdam Declaration was, Dr. Childers said, “vague and evasive.” Truman considered it a rejection. He added that a blockade and terror bombing, both of which had already occurred, failed to produce results.

Truman felt he was out of options and ordered the bombing.

Complete and Utter Devastation

“Colonel Paul Tibbets, Jr., at the controls of the Enola Gay, took off from Tinian in the Marianas carrying a 9,000-pound bomb with the destructive power of 20,000 tons of TNT,” Dr. Childers said. “The bomb tumbled from the bomb bay just after 8:15 [a.m.]. When it reached a point 660 yards from the ground, a blinding flash illuminated the sky, and a split-second later a gigantic fireball burst over the unsuspecting city.”

Dr. Childers said that shockwaves of incredible force “roiled like a typhoon of scalding air.” The shockwaves leveled virtually everything in their path and the first mushroom cloud “rose to an altitude of 55,000 feet.” Initial casualties were estimated at 100,000, a figure which would double within 18 months due to radiation fallout.

“In his logbook [on August 6], Robert Lewis, the copilot of the Enola Gay, wrote simply, ‘My God,’” Dr. Childers said. “Beneath the cloud, 60% of what had been the city of Hiroshima disappeared.”

This article was proofread and copyedited by Angela Shoemaker, Proofreader and Copy Editor for The Great Courses Daily.

Dr. Thomas Childers contributed to this article. Dr. Childers is Sheldon and Lucy Hackney Professor of History at the University of Pennsylvania, where he has been teaching for over 25 years. He earned his bachelor’s and master’s degrees from the University of Tennessee and his PhD in History from Harvard University.