TRANSLATION OF THE “Z” PLAN
One of the greatest contributions of the MIS
during World War II was the translation of the captured “Z”
Plan. The “Z” Plan contained Japan’s strategy
and tactics for an all out counterattack against the Allied forces
specifically in the Mariana Islands, which was located south west
of the Hawaiian Islands and north east of the Philippines.
The “Z” Plan was discovered on March 31, 1944 after
two planes crashed into the sea off the southern Philippines
carrying Admiral Mineichi Koga (who became the commander in chief
of the Japanese Combined Fleet after the death of Admiral Isoroku
Yamamoto) and Vice Admiral Shigeru Fukudome. Admiral Koga perished
but Filipino guerrillas in the area picked up Vice Admiral Fukudome
who had in his possession a document contained in a waterproof
container. Fukudome and the document were turned over to the American
forces.
The American forces soon realized the document’s importance
and sent it to the Allied Translator and Interpreter Section (ATIS)
in Indooroopilly, located in Brisbane, Australia. Nisei
translators Yoshikazu Yamada and George “Sankey” Yamashiro,
along with officers John E. Anderton, Faubian Bowers and Richard
Bagnall, were put to the task of translating the document. Copies
of the translated documents were then sent to every American Naval
officer in the Pacific. The Japanese did not know that the “Z”
Plan, as it was named, had been captured. The “Z”
Plan was termed, “the most significant enemy document seized
during the war” by military historians.
Thanks to the translated “Z” Plan, when the Marianas
were invaded in June 1944, American troops already knew the strategy
of the Imperial forces. The neighboring Mariana Islands was strategically
located to serve as an air base for the Army Air Corps’
long-range bombers to make non-stop strikes on Japan. Because
of this, American forces constructed air bases on the islands
of Guam and Saipan.
In the battle of the Philippine Sea, known as the “Great
Marianas Turkey Shoot,” the Japanese Imperial Forces suffered
a devastating loss of more than 450 planes and 400 pilots. This
great victory was due mainly to the translation of the “Z”
Plan.
