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Operations MO MI AL

Posted: Wed Feb 19, 2020 4:05 pm
by marcelo_malara
Hi guys. I am curious about these names given by the Japanese to the operations of Port Moresby, Midway and Aleutians. They are found in every book. Question is, what were the originals names in Japanese language? Would they be so dumb as naming the ops with the first letters of the target...?


Re: Operations MO MI AL

Posted: Fri Feb 21, 2020 10:47 am
by wadinga
Hello Marcelo,

These names were merely pre-war outline contingency plans much like the US Rainbow codes, but were superceded by actual, less obvious, operational codenames once they became reality. It would have been unforgivably stupid to link the peacetime contingency name with the wartime target.

"RZP Campaign" was the operational codename for the Port Moresby campaign and this ... -campaign/

gives the story of identifying the target from this uninformative codename. The trick in confirming "AF" as the codename for Midway by seeding the idea that freshwater was running short there and then looking for references for this in decoded Japanese transmissions is well known, even making it into the movies (Battle of Midway and Midway).

But then sometimes the unbelievably stupid actually happens. In Part 3 of the Midway story on the stationhypo site is this revelation:
One such key break-through occurred as early as January 18, 1942 — a mere month after Station HYPO had been given responsibility for breaking the operational code. Dyer and Wright had revealed enough of the code groups in three intercepts to allow for partial translation. Common to all three was one particular code group which Rochefort translated as “koryaku butai,” or, “assault landing force.” Preceding the code group was the letter “R.” Rochefort believed, and Nimitz’ intelligence officer agreed, that the “R’ was Rabaul. Based on his knowledge of the current disposition of Japan’s forces — courtesy of his traffic analysts and ship plotters — Rochefort deduced that Nagumo was going to head south from Truk, attack New Britain and occupy Rabaul.
So Duh? Yes sometimes the Japanese were that stupid, as were other every other nation, because in war everybody makes mistakes and the winner usually makes the fewest.

All the best


Re: Operations MO MI AL

Posted: Fri Feb 21, 2020 7:04 pm
by marcelo_malara
Thanks Wadinga, very informative. Now I am thinking why the authors of all these books don´t use the wartime plan name...