Parsons’ Priorities

July 17, 2019 will mark the 75th anniversary of the Port Chicago disaster

Preliminary Examination of Parsons’ Preliminary Memo from Port Chicago


Pretend we’re in a courtroom. You are a member of the grand jury in the cold case of ‘The Port Chicago Witness (PCW) versus Traditional Historical Accounts’. Your task is to consider whether or not there is reason for a closer investigation of the theory that a nuclear bomb was tested at Port Chicago on July 17, 1944.

The “Prosecution” is about to take testimony on the memorandum marked Exhibit 1. The following questions focus specifically on the opening and close of the two-page memo excerpted below. (The memo is a real document. Click on the link to read it in its entirety.)

Exhibit 1 –  William S. Parsons, Memorandum on Port Chicago Disaster

excerpts from the MEMORANDUM

24 July 1944
Rear Admiral W. R. Purnell, USN
From: Captain
W. S. Parsons, USN
Subject: Port Chicago Disaster, Preliminary Data

1. On 20 July I arrived in San Francisco . . . my mission was to obtain data on effect rather than the cause of the detonation . . .  

. . . Comparing loss of life to the Halifax disaster . . . If the two explosions are considered to be of the same order of magnitude, the difference in loss of life can be attributed to the fact that Port Chicago was designed for large explosions.

W. S. Parsons
Captain, USN


Hearsay witness (i.e. history writer) James Campbell, author of the The Color of War , is on the stand to testify about the Port Chicago memo, Exhibit 1.

In his July 24, 1944 memo to Rear Admiral W. R. Purnell concerning the explosion that took place four days earlier, Captain W. S. Parsons, USN stated that “‘Port Chicago was designed for large explosions.’

Mr. James Campbell, how would you interpret that statement?

How One Battle Broke Japan and Another Changed America

James Campbell


“In early February 1942, the Navy began construction. Its plan was to make Port Chicago the only war-scale shipping point on the West Coast deliberately located and designed to minimize the dangers of an accidental explosion…”

The Color of War, p57

Prosecution: Pardon me? Are you saying, James Campbell, that “designed for large explosions” actually means “designed to minimize the dangers of an accidental explosion”?


for large explosions =
designed to minimize the dangers
of an accidental explosion

If Campbell’s interpretation is right, the phrase “designed for large explosions” means the blueprint for the Port Chicago Naval Ammunition Depot included features that would reduce the potential hazards in the unfortunate case that some explosives were to detonate unintentionally.”  

Which (almost) makes perfect sense — as much sense, at least, as the poor safety conditions at the essential ammunition depot that supplied the war in the Pacific. As if there wasn’t danger enough, the men loading the high explosives onto the ships were untrained young Negro seamen working under the authority of inexperienced White officers. So go figure — “green” stevedores, White officers, black powder . . . the old cliche applies: Port Chicago was an accident waiting to happen.


But what if Captain Parsons meant exactly what he wrote in the two-page memo dated one week after the Port Chicago explosion? Was Port Chicago designed for large explosions — like the massive blast of July 17, 1944?  

Apparently Captain Parsons had done his homework about the history of the Naval Ammunition Depot.

Parsons was the head of ordnance at Los Alamos. He was the man — somehow hidden in history — who was responsible for producing “the perfectly delivered, perfectly functioning bomb that could end the war.

What was he doing at Port Chicago?

As noted in the memo, Parsons said his mission was “to obtain data on effect rather than the cause of the detonation…”

In Target Hiroshima: Deak Parsons and the Creation of the Atomic Bomb,  biographer (i.e. hearsay witness) Al Christman explains that Parsons’ visit to the scene of the disaster was a self-imposed task. It wasn’t necessary for him to be there, he just felt a need “to see for himself.” Christman says,

“Parsons’ Port Chicago trip was not a major incident in Project Y history despite subsequent sensational attempts by a historical revisionist to make it so. Parsons’ appearance at the site, plus the report of a mushroom cloud, contributed to erroneous charges starting in the 1980s that this had been a nuclear explosion and hence the subject of a government coverup.”

Target Hiroshima, p 155

Christman points out that the discredited story shows up every now and then even though it was clearly debunked by established historians and scholars. So that settles that.

Or does it?


Why was Parsons interested in the effect and not the cause of the explosion?

Granted the Port Chicago explosion has been billed as “the greatest homefront disaster of WWII, but how could that data — presumably standard facts about the impact of a conventional explosion — be useful in the development of the atomic bomb?

And if it was, couldn’t he have learned as much by visiting the scene of the fatal explosion at West Loch, Hawaii (Pearl Harbor’s West depot) only a month earlier?  

That will be one line of questioning when we ‘interrogate’ Captain Parsons in a future post (i.e., examine primary documents written by him). We’ll also ask:

  1. How did he react when James Conant and other Project leaders decided to stop work on the gun assembly plutonium bomb he had been working on with great urgency?
  2. Why was he absent from the meeting held  on July 17, 1944 at the Metallurgical Laboratory,  University of Chicago where that momentous decision was made?

It might be interesting to know (but we may never find out)  Parsons’ whereabouts on the 17th, three days before his arrival in San Francisco with Captain Jack Crenshaw. (Parsons’ brother-in-law, a long-time friend, served on the three-man Court of Inquiry that began holding hearings on the 21st.)  


As for his disappointment with the effect of the explosion, it’s not clear what Parsons was expecting —  or why he expected anything at all. At any rate, Christman reports that

“Based on his observation of the Port Chicago explosion, Parsons assured [General Leslie] Groves that the reaction of foreign observers to the desert shot would be one of “intense disappointment.” He noted “even the crater would be disappointing.”

Target Hiroshima

The Trinity test conducted by the Manhattan Project on July 16, 1945 at Alamogordo, New Mexico —  now famous as the first full-scale detonation of an atomic bomb — was under consideration at the time. Parsons disparaged the idea. He told Groves that

“The principal difficulty with such a demonstration is that it would not be held one thousand feet over Times Square, where the human and material destruction would be obvious, but in an uninhabited desert, where there would be no humans and only sample structures.”

Target Hiroshima

Christman adds “To Parsons the demonstration idea was an invitation to “a political and military fizzle, regardless of the scientific achievement.’”  

A political and military fizzle? We certainly couldn’t have that. Not by any means.

In a future post perhaps we can clarify what is meant by “his observation of the Port Chicago explosion.”


observe the explosion =obtain data on the effect of the detonation

If the ‘prosecution’ were to rest at this point in the case of The PCW v. Traditional Historical Accounts, the closing statement would emphasize the importance of the Manhattan Project leadership meeting in Chicago on July 17, 1944, the very date of the Port Chicago explosion. (The coinciding events also share the mid-July anniversary of the Trinity test.)


The coincidence is not just the timing of the historic events. Of equal interest is the subject of the meeting: the plutonium gun-assembly bomb. Called the “Thin Man,” the long heavy weapon was supposedly named after President Franklin D. Roosevelt; the “Fat Man” was named after Great Britain’s Prime Minister / Minister of Defence, Winston Churchill.)

The Thin Man was the first bomb produced by the ordnance division at Los Alamos, under the leadership of Captain Parsons. The gun assembly bomb, which could be used with either plutonium or uranium, was his priority from the time he joined the staff at Los Alamos in May 1943 until the design was set aside in favor of an implosion model.

Plutonium was a better choice for the bomb than uranium. In the first place, the man-made element — discovered in 1940 by scientists researching atomic fission — would be more readily available than uranium. Plutonium would also produce a more dynamic explosion.

But an unresolvable problem cropped up. In April 1944 theoretical physicists (scientists, like Albert Einstein, who do mathematical calculations, not experiments) established the certainty that plutonium would predetonate in a gun assembly bomb. Predetonation, or ‘spontaneous fission’ meant that the bomb would “fizzle.”


Richard Rhodes

It doesn’t help that the potentially confusing word “melt” is sometimes used in explanations of the problem. An ordinary reader (like The PCW) with no background in science might reasonably conclude that a fizzle was a dud that would simply fail to explode, a firecracker with no crack.

Not so, says Richard Rhodes, author of the award-winning book The Making of the Atomic Bomb.

“ . . . an admixture of plutonium 240 and higher isotopes in Hanford reactor-bred plutonium made that material so unstable that a stack fired up a gun barrel even at 3,000 feet per second would melt down before it had time to mate and explode at full yield.” [emphasis added]

The Atomic Bomb and Its Consequences

Because of this “melt down” the bomb would be ineffective. ‘Ineffective’ may seem to imply that the bomb would not work at all; inefficient is a more accurate term. As Rhodes explains “ . . . even a fizzle would release energy equivalent to at least sixty tons of TNT.”  

Top: A nuclear chain reaction (as depicted in The Smyth Report)

Bottom: predetonation from spontaneous fission: a fizzle

Ah! So a bomb that fizzles still creates an effect. Aha! Let's revisit the Thin Man.   


Although he became aware of the predetonation problem in April 1944, Oppenheimer didn’t tell [James] Conant right away. (Conant was chairman of the National Defense Research Committee (NDRC), the agency that administered all of the government’s science research projects during the war, including the Manhattan Project.)

For a few months efforts were made to find a way around the problem, but finally

“Oppenheimer informed Conant of the 240 [plutonium contamination] problem  in early July. To decide how best to deal with it, Conant took immediate steps to assemble project leaders for a conference at the Metallurgical Laboratory on the seventeenth.

Besides Conant, the following were in attendance: Oppenheimer, Compton, Charles A.Thomas… Fermi, Groves, and Nichols. After some deliberation, the group decided that the predetonation threat posed by 240 made the use of plutonium in the gun-type bomb impracticable and work on this system should be suspended immediately.”

Manhattan: The Army and the Atomic Bomb

A whole year’s worth of urgent work was scrapped with the Thin Man bomb.

The target date for uses of the first bomb had to be reset from midsummer 1944 to some time in 1945.

The Project was reorganized; implosion, an emerging new concept in bomb design, became the priority.  


The Thin Man gets short shrift in Manhattan Project histories. Writers probably gloss over the original bomb because, they say, it couldn’t be used due to the spontaneous fission.

It couldn’t be used as an effective combat weapon, that is. But there’s a lot that is not reported about the original Thin Man bomb. Was it fully developed before it was shelved? Was it ever tested, or did the Oppenheimer and Conant base their decision on the mathematicians’ calculations ?

In any case the intense effort to produce the Thin Man by the summer of 1944  was not a total waste. It showed (somehow) that the gun assembly design was certain to work when plutonium was replaced with uranium. There was therefore no need to proof-test the u-gun before it was used in combat.

The first of the two atomic bombs used against Japan was the uranium gun bomb known as the “Little Boy”.  In his tell-all book Now It Can Be Told, Groves explains that “The Little Boy was known variously as the Thin Man, the Skinny One, and a number of similar names…”  

Rhodes refers to the Little Boy as the Thin Man’s “modest brother”.

Twin, brother, father — whatever it was called, the Thin Man had the same genetic makeup as the Little Boy. The size and shape had to be modified but — as with differing versions of history — the main difference was the vital substance on the inside.


As noted above, Captain Parsons was disappointed in the effect he observed at Port Chicago. He   wasn’t discouraged though. On July 4, 1944 he had already begun working on ideas for future tests of nuclear bombs against naval ships.

Atomic cloud during “Able Day” blast at Bikini Atoll.  

The Navy also played an important role in the post-war nuclear program. Deak Parsons had done research during the war on theoretical nuclear attacks on ships, including investigation into the 1944 Port Chicago disaster in which 320 sailors were killed after munitions aboard a cargo ship detonated. In 1945, Parsons formed the Navy Atomic Bomb Group, and began to push for tests of bombs above and below ships.

The Navy in the Manhattan Project
The American Heritage Foundation


Commodore Parsons was a creative visionary, a charming and diplomatic man who was accustomed to having his way. Some of his colleagues had opposed underwater nuclear testing. One of the dissenters was Stafford Warren, the doctor in charge of safety for the Manhattan Project. He was concerned that the test would be too hazardous.

Parsons understood.

He pointed out several adjustments that would have to be made in order to conduct the tests.

For one thing, he said, the location for the test would have to be carefully chosen, and he concluded that the decision makers responsible for the test would most likely exercise due caution. They would probably only conduct the test if it was really necessary.

They would, of course, take radioactive hazards “fully into account.”

Commodore Parsons (soon to be “Atomic Admiral” Parsons) was Deputy Task Force Commander for Technical Direction when Operation Crossroads took place in July 1946 — almost a year to the day after the Trinity test, two years after the explosion at Port Chicago.


The Able shot, the first of two tests conducted, turned out to be — well, disappointing.  

“In July 1946, Life magazine reported that “a large number of scientists are looking forward to the forthcoming explosion…

The Able test detonation, originally scheduled for May 15, was postponed six weeks to allow, according to some opinions, for Congressional observers to be on the scene…

The New York Times’ account of Able noted that while the bomb had exploded with a flash “ten times brighter than the sun” over the target ships, “only two were sunk, one was capsized, and eighteen were damaged.”

The foreign observers were unimpressed, reported the press; the Russian observers shrugged their shoulders and the Brazilian observer said he felt “so so” about the blast. Of the 114 press representatives at Bikini, only 75 stayed for the Baker test.

James P. Delgado
The Archeology of the Atomic Bomb
National Park Service 1991

And the rest of the history…is being acted out on the world stage today.


The PCW does not suggest that the information in this post (with its various sources) is conclusive evidence that a nuclear bomb was tested at Port Chicago. In the large body of evidence yet to be revealed this is just the tip of a baby-finger print.

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