WI hiroshima-type bomb was used in June 1945.

raharris1973

Gone Fishin'
Donor
Monthly Donor
IIRC in a what-if anthology on WWII with snippets written by military
historians including Carlo D'Este, Dennis Showalter, David Glantz and
others, one of the authors noted that field testing for the Hiroshima
device was not necessary (the physics were proven in a 1943 chain
reaction experiment) and Alamogordo tested only the Nagasaki device,
ie, Hiroshima did not need to wait for Alamogordo. They reasoned that
the Hiroshima bomb could have been made ready for launch in July 1945
or possibly late June.

What if Hiroshima was bombed in late June 1945? What if it takes many
weeks before any other bomb can be used? Will the surrender of Japan
be speeded in any way? Will the Soviets still enter the war? If they
do, will their campaign go the same resulting in the same zones of
occupation?


On a separate but related note:
AH challenge - Make at least 2 Hiroshima style atomic bombs available
by April 1945.
 

Kiwiguy

Banned
After Hiroshima was bombed, Japan's leading nuclear physicist Yoshio Nishina was sent to examine Hiroshima and report back whether it was a nuclear device.

Nishina confirmed that it was, but also advised not to worry as it was impossible for USA to have two A-bombs.

If you believe some accounts from US intelligence records, Japan then test blasted their own A-bomb out to sea from Hungnam, Korea.

The radio operator on U-234, Hirsch (or Hischfeld) claimed after the war that there had been an even earlier Japanese nuke test.

Without Nagasaki the Japanese High Command were not convinced they needed to surrender.
 
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