‘The Most Terrible Weapon’ and ‘A Very Pleasant Way to Die’
The Posting
The National Security Archive, a research institute in Washington, D.C. published a posting on August 8, 2022, titled “77th Anniversary of Hiroshima and Nagasaki Bombings: Revisiting the Record.” It supplements an earlier Archive posting, “The Atomic Bomb and the End of World War II,” adding material the Archive says had been declassified for decades but was hard to locate: internal Manhattan Project papers and a U.S. Navy assessment of the bombings’ medical effects. The compiled documents run from 1944 to 1946, covering what the posting calls “the problem of radiation effects,” from the Trinity test in July 1945 to the bombings of Japan.
Two documents in that compilation are themselves hard to pin down. The Navy report carries no named author and no date. General Leslie Groves’s Senate testimony does carry a date, but the Archive’s own documents disagree on what it is: one page states the testimony was given on November 28, 1945; a companion document header for the same testimony lists November 30, 1945. The discrepancy is not resolved anywhere in what has been released.
What Japanese Press Accounts Said
The bomb detonated over Hiroshima on the morning of August 6, 1945, sending the cloud to roughly 20,000 feet (6,100 meters); a second device struck Nagasaki on August 9, 1945. In the weeks that followed, Japanese newspapers reported that people in both cities continued to die, and that survivors continued to fall sick, well after the blasts themselves, describing a slower illness rather than an injury from heat or force, with symptoms recorded appearing days or weeks afterward. The specific outlets and exact publication dates are not identified in what has survived into this release. The record establishes that these reports existed and reached U.S. officials, not whether every detail in them was accurate.
The Official Characterization
In a later posting marking the bombings’ 80th anniversary, published September 25, 2025, the Archive states plainly that Groves dismissed the Japanese press reports as propaganda. That is the Archive’s own historical judgment, written in 2025, about how Manhattan Project leadership is understood to have treated the reports, not a line quoted from a 1945 memo. The 2022 compilation does not contain a document in which an official uses the word “propaganda” about these specific reports. The characterization and the primary record are two different things, and the file does not show which internal document, if any, the word is drawn from.
Two Sentences, Side by Side
The Navy’s assessment, nested in the 2022 compilation without an author’s name or a date, is built around a single judgment: the atomic bomb is “the most terrible agent of destruction known to man.” General Groves, testifying before the Senate Special Committee on Atomic Energy, a body the Senate formed in late 1945 to draft legislation on how atomic energy would be governed, told the senators that radiation sickness, where it did not kill a victim outright, came “without undue suffering.” He went further: “In fact, they say it is a very pleasant way to die.”
Both statements sit inside the same released file. Nothing in the record connects them, qualifies one against the other, or explains how the same wartime apparatus produced a weapon it called the worst ever devised and a death from that weapon it called pleasant.
What the Internal Material Says About Itself
The Archive describes the 1944-1946 internal papers as addressing “the problem of radiation effects,” indicating the subject was under some form of active review inside the Manhattan Project before the war ended. What that review concluded is not detailed in what has been released. The Archive also states that the Navy’s report, with its line about the bomb as the most terrible weapon known to man, caused Groves to cut off early discussion of the issue inside the Manhattan Engineer District, the Army’s administrative name for the bomb program. No document in the released material records when that cutoff happened, who else was party to the discussion, or what, if anything, replaced it.
The Gaps, Named
The Japanese press reports are not attributed to any named outlet or date. Groves’s Senate testimony carries two conflicting dates in the Archive’s own materials, with no note reconciling them. The Navy report is referenced only by the line used to title it; no author’s name and no date appear anywhere in the release. And nothing in the file indicates whether the propaganda framing, as the Archive later described it, was ever revisited inside the Manhattan Project once its own medical teams reported back from Japan. Each of these is a fact about the paperwork that survived; none says anything about what is missing from it.
What Doesn’t Fit
Calling a weapon the most terrible ever built, and calling death from that weapon pleasant, are not small differences in tone. They describe the same mechanism, from two offices of the same government, in opposite registers, within months of each other. The record contains no internal memo reconciling the two positions, no sign that either office was responding to the other, and no later document correcting one in light of the other.
There is an ordinary explanation worth stating: a Navy report assessing a weapon for strategic purposes and a general testifying to a Senate committee weighing further funding and oversight have different audiences and incentives, and might reasonably describe the same weapon differently. The file does not confirm that explanation. It does not contradict it either.
Writing afterward, the historian Sean Malloy found, drawing on Manhattan Project records, that the teams Groves sent to Hiroshima and Nagasaki within a month of the bombings concluded that radiation was a significant factor in wartime deaths there, a finding that sits uneasily beside Groves’s Senate answer to Senator Warren Austin’s question about residue: “there is none. That is a very positive ‘none.'” Contemporary press coverage of the hearing was thin. The Washington Post and the New York Times did not report the radiation testimony at all; the Washington Evening Star covered it but repeated Groves’s claims without challenging them. Later historians were more pointed: Peter Wyden called the testimony an “outrageous untruth”; Eileen Welsome called it “patently untrue.” Those are judgments made afterward, not findings inside the file itself. What the file shows is two official voices, on the record, describing the same thing in terms that do not sit together, and no document showing anyone inside the Manhattan Project ever tried to make them.