ATIS linguists translate Japanese plan

Courtesy Photo | Page 11 of the ATIS-translated Z Plan shows the Japanese air strength at its bases throughout the Central Pacific. (Courtesy photo by National Archives)  

FORT HUACHUCA, AZ, UNITED STATES

05.23.2022

Courtesy Story

U.S. Army Intelligence Center of Excellence

by Lori S. Stewart, USAICoE Command Historian

On May 23, 1944, five linguists with the Allied Translator and Interpreter Service (ATIS) in the Southwest Pacific Area completed their translation of the captured Japanese Z Plan. The document fully outlined the Japanese Combined Fleet’s plan to counterattack any advancing American naval operation in the Marianas Islands. Because of the timely translation and dissemination of the Z Plan, the U.S. Navy soundly defeated the Japanese fleet in the Battle of the Philippine Sea.

Believing Japan needed a decisive naval engagement to defeat the United States, Admiral Mineichi Koga, commander-in-chief of the Japanese fleet, devised a new operations plan in early 1944. His “Z Plan” laid out in detail the strategic distribution of all Japanese air and sea forces around their “last line of defense,” the Marianas in the South Pacific. Shortly after his plan, officially titled “Secret Combined Fleet Orders Operation No. 73,” was published, Koga and his chief of staff, Rear Admiral Shigeru Fukudome, flew in separate planes to Davao in the Philippines to establish their new headquarters. On March 31, 1944, both planes encountered a severe tropical storm. Koga’s plane crashed and was never located while Fukudome’s plane crashed into the sea near Cebu. Fukudome and his briefcase carrying the Z Plan were captured by Filipino guerillas.

The Japanese, desperate to locate Fukudome and the documents, offered a reward and threatened dire consequences if they were not returned by May 30. While the American commander of the local Filipino guerillas, Lt. Col. John Cushing, negotiated the return of the Japanese rear admiral, Fukudome’s briefcase was making a surreptitious trip from Cebu to Brisbane, Australia. On May 21, it landed in the hands of Col. Sidney Mashbir, the director of ATIS. Mashbir had all the documents photographed and the originals rushed back to Cebu for return to the unsuspecting Japanese.

Meanwhile, responsibility for translating highly classified documents typically fell to ATIS’s officers, and Mashbir immediately assigned three of his best—Maj. John Anderton, 1st Lt. Faubian Bowers, and Lt. Richard Bagnall (U.S. Navy)—to the contents of the briefcase. Within twenty-four hours, they had a rough translation of the plain text document that, in an unusual move, was given a final review by two enlisted Japanese American linguists—S. Sgt. Kiyoshi “George” Yamashiro and T3g. Yoshikazu Yamada. Mashbir gave the translation a final edit and then had two typists transcribe the handwritten translation. Colonel Mashbir then personally turned the crank on the mimeograph machine, turning out thirty-two copies of the twenty-two-page “’Z’ Operations Orders Limited Distribution Translation No. 4” on May 23, 1944.

Several copies of the translation were rushed to Admiral Chester Nimitz, commander-in-chief of the Pacific Fleet in Pearl Harbor. Because the ATIS translators were not familiar with Japanese naval terminology, Admiral Nimitz requested a retranslation of the sensitive document by the translators in the Joint Intelligence Center, Pacific Ocean Areas (JICPOA). Once the second translation was complete, Admiral Nimitz had it rapidly distributed to every flag officer involved in the upcoming Marianas invasion.

On June 19, while American troops battled the Japanese on Saipan, the U.S. Navy launched its attack on the Japanese fleet in the Philippine Sea west of the Marianas. With the Z Plan, the U.S. Navy had solid intelligence about the Japanese plan for counterattack as well as the strength, composition, and location of almost all the Japanese air and sea forces. Consequently, the Battle of the Philippine Sea on June 19-20—the largest carrier battle of the war—resulted in a major Japanese defeat from which they could not recover.

• Date Taken: 05.23.2022
• Date Posted: 05.23.2022 11:38
• Story ID: 421281
• Location: FORT HUACHUCA, AZ, US