A Second Sun Rises
By Mike Bennighof, Ph.D.
March 2022

Modern Japanese politicians have been known to declare their country to be the only nation to ever have been targeted by nuclear weapons. And while the atomic attacks on Hiroshima and Nagasaki killed tens of thousands of civilians and caused widespread devastation, the Japanese Empire had been perfectly willing to use these weapons itself, if only it could create them.

Serious work on high-energy physics began in Japan in 1931, under the leadership of Dr. Yoshio Nishina. The Riken institute in Tokyo headed the efforts, which gained from Nishina's international reputation. Nishina, a friend of Albert Einstein and Niels Bohr, attracted a great deal of international assistance and the institute built a series of ever-larger cyclotrons and also purchased one from the University of California at Berkeley.

Nishina believed that the Americans would soon start work on nuclear weapons, and urged the Japanese Army to initiate its own program. Meanwhile, the Japanese Navy had its own program under the leadership of Bunsaku Arakatsu and Hideki Yukawa, the first Japanese recipient of the Nobel Prize in physics. The Navy program was not aimed at weapons, but instead at developing nuclear power to replace the oil that fueled warships.

	Yoshio Nishina, in his later years.

The Army authorized Nishina to begin a weapons program in October 1940, and he developed and built gaseous diffusion separators to enrich uranium. While a cyclotron can enrich uranium, it can't do so at anything near the scale necessary for a nuclear weapon, and uranium must be enriched to produce an explosion. Gaseous diffusion technology was developed independently in the United States as part of the Manhattan Project, with separators in Oak Ridge, Tennessee, and in Germany as well. Diffusion has since been developed into gas centrifuges, the technology used by Pakistan and Iran in their current nuclear programs.

Without the gas centrifuge, developed long afterwards, the diffusion methods practiced by Nishina could not have delivered enough enriched uranium for a bomb in anything close to the time frame the Japanese war effort required. But that was not the only problem — the Japanese could not secure enough uranium for their purposes. Small amounts were found in Korea and Burma, but only enough for experimentation. And in the 1940s, uranium was barely known to the public, much less found on the black market.

Hideki Yukawa, Nobel laureate.

Germany, however, possessed uranium from its own sources as well as Czech ones. Though not as pure as that mined found in North America, the Germans were able to refine the ore for their own program. In the summer of 1943 the Japanese asked for some, telling their Axis partners it was for peaceful purposes. They also — in one of the rare instances of inter-service cooperation — combined the two nuclear programs into one with the sole purpose of delivering a working atomic bomb. Known as Project F-Go, the nuclear physicists never received the massive funding of the American Manhattan Project, and appear to have spent the war conducting laboratory experiments.

The lunatic fringe has claimed for some decades that the Germans sent massive amounts of uranium to the Japanese, but only one shipment can be confirmed: 560 kilograms of uranium oxide dispatched in April 1945 aboard the submarine U-234. Contrary to her special orders, she surrendered to the U.S. Navy off the Maine coast on 10 May. The shipment would have given the Japanese less than 10 percent of what they needed to create a viable bomb; in the days before Hiroshima, a "dirty bomb" of the type trumpeted by modern scare-mongers had not been considered. Two Japanese technical experts returning from tours of German shipyards and aircraft factories killed themselves rather than join the Germans in surrender. One U.S. Navy sailor, accidentally shot in the buttocks by a comrade, died a week later from internal bleeding.

	Atomic submarine U-234 is escorted into Portsmouth, New Hampshire. Contrary to recent, and fairly idiotic, television news reports, she did not carry bomb-grade uranium.

The war ended with Japan's program far from creating a bomb; American bombers smashed the Riken laboratories in April 1945 and they were never re-constituted. American occupiers threw Nishina's two surviving cyclotrons into Tokyo Bay that fall, and the confiscated uranium oxide from U-234 apparently helped create more American bombs (though it is extremely unlikely that this uranium was dropped on Japan). The Atlanta Constitution, paragon of Southern journalism that it was, reported in October 1946 that the Japanese had detonated an atomic bomb in August 1945 off the Korean coast, but this apparently was a tale spread by destitute Japanese officers seeking payment from a gullible reporter.

We did not include a Japanese atomic bomb in Great Pacific War because it wasn't a very likely possibility. But at least some in the Japanese power structure believed it to be, and historical games are not — protestations of some aside — about what happened. To truly work as historical models, they have to be based on what participants thought could happen. And both the Japanese and American intelligence believed a Japanese atomic bomb was possible. Not likely, but possible.

The Variant

The Japanese player must expend 40 BRPs in the Spring 1943 turn and 10 more BRPs every Spring turn thereafter until the Project F-Go marker is drawn. The marker itself is not placed in the container until the Summer 1945 turn.

If the marker is drawn, the Japanese player rolls one die. On a result of 6, enough uranium has been obtained to make a bomb. During each Japanese Naval impulse, the Japanese player may designate one SUB factor to make a nuclear suicide attack. The submarine may attack any hex or port adjacent to the sea area it occupies.

If the United States West Coast box is attacked, reduce the American BRP base by 15. If Vladivostok is attacked, reduce the Soviet BRP base by 15. If any other objective hex on any of the three Great Pacific War maps is attacked, reduce the owning country's BRP base by 5.

If a hex containing enemy ground units is attacked, all are reduced or eliminated. If a hex containing air or naval factors (of any type) is attacked, the owning player rolls one die for each factor. On a result of 1 through 4, it is destroyed.

The Japanese SUB factor is destroyed by the nuclear attack as well. Add five to the Japanese surrender die roll if the Japanese player has conducted a nuclear attack.

Place a mushroom cloud marker in any hex attacked by nuclear weapons. No units other than air units may enter the hex for the rest of the game; air units may not be based there.

You can download the new political markers, and some mushroom cloud markers, by clicking here.

Great Pacific War returns soon in a Final Edition. For a limited time, Gold Club members can snag an upgrade kit with a new scenario book and full-color play aids.

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Mike Bennighof is president of Avalanche Press and holds a doctorate in history from Emory University. A Fulbright Scholar and NASA Journalist in Space finalist, he has published a great many books, games and articles on historical subjects; people are saying that some of them are actually good. He lives in Birmingham, Alabama with his wife, three children, and his Iron Dog, Leopold.

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