Z Plan (Japan)
Encyclopedia
The Z Plan is a set of captured World War II
documents describing Japanese military plans to counterattack the Americans in the central Pacific ocean
for one last decisive battle. The capture and exploitation of this information was one of the most important military intelligence
achievements of the Pacific War
.
The Z Plan was developed under the leadership of Admiral Mineichi Koga
, commander in chief of the Japanese Combined Fleet, and was approved by the Imperial Japanese Navy General Staff
. The plan was formally titled: Combined Fleet Secret Operations Order No. 73, with the final version issued on March 8, 1944. On April 1, en route to Davao
, Admiral Koga's plane crashed into the ocean during a bad storm, killing Koga and everyone else aboard. Admiral Koga's chief of staff, Rear Adm. Shigeru Fukudome
, carrying a copy of the Z Plan, was traveling the same itinerary in a separate plane. This second plane crashed near Cebu Island
after attempting to avoid the same storm. Fukudome and nine others eventually made it to shore, where they were captured by local Filipino guerrillas who were supportive of the U.S. forces.
Because of the loss of the two planes, with their high-level occupants and important documents (Japanese ocean-current experts believed documents would eventually wash-up on shore), the Japanese applied intensive pressure on the local population. Partially as a result of this pressure, Fukudome and the others were eventually released.
On April 3, a wooden box from Fukudome's plane washed up near shore, and was secretly recovered by two villagers. The box contained the Z plan, a bound document in a red leather portfolio, with a Z on the cover. The documents eventually made it into the hands of the local guerrilla organization, the Cebu Area Command, under Lt. Col. James M. Cushing. The ornate nature of the documents led the CAC and their American handlers to suspect the documents were very important, a suspicion that was later reinforced by Japan's offer of a large reward for the return of any documents.
A clandestine high-priority submarine
pickup was arranged, with a cover story
of evacuating American refugees. The submarine picked up the documents, along with 40 American men, women and children. Traveling mostly on the surface for speed, and diving only when needed, the submarine survived depth charging twice, arriving near the American naval base in Darwin, Australia on May 19. From there the documents were flown to Brisbane.
The Z Plan documents were in plain text
, rather than code, and were translated on an urgent basis by the top five translators at the Military Intelligence Service
attached to the Allied Translator and Interpreter Section
, it was first translated by Yoshikazu Yamada and George "Sankey" Yamashiro, two nisei
translators. Copies of the translation were rushed to General Douglas MacArthur
, who quickly forwarded them to Admiral Chester Nimitz
, commander in chief of the Pacific Fleet (and Admiral Kogo's counterpart). Among other things, planned Japanese diversionary tactics were now anticipated by the Americans, leading to the lopsided American victory in the Battle of the Philippine Sea
, the largest aircraft carrier
battle in history, and one of the decisive battles of the Pacific war.
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
documents describing Japanese military plans to counterattack the Americans in the central Pacific ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
for one last decisive battle. The capture and exploitation of this information was one of the most important military intelligence
Military intelligence
Military intelligence is a military discipline that exploits a number of information collection and analysis approaches to provide guidance and direction to commanders in support of their decisions....
achievements of the Pacific War
Pacific War
The Pacific War, also sometimes called the Asia-Pacific War refers broadly to the parts of World War II that took place in the Pacific Ocean, its islands, and in East Asia, then called the Far East...
.
The Z Plan was developed under the leadership of Admiral Mineichi Koga
Mineichi Koga
- Notes :...
, commander in chief of the Japanese Combined Fleet, and was approved by the Imperial Japanese Navy General Staff
Imperial Japanese Navy General Staff
The was the highest organ within the Imperial Japanese Navy. In charge of planning and operations, it was headed by an Admiral headquartered in Tokyo.-History:...
. The plan was formally titled: Combined Fleet Secret Operations Order No. 73, with the final version issued on March 8, 1944. On April 1, en route to Davao
Davao
Davao refers to several closely related places in Mindanao in the Philippines. The term is used most often to refer to the city.*Davao Region, an administrative region*Davao del Norte province*Davao del Sur province*Davao Oriental province...
, Admiral Koga's plane crashed into the ocean during a bad storm, killing Koga and everyone else aboard. Admiral Koga's chief of staff, Rear Adm. Shigeru Fukudome
Shigeru Fukudome
- Notes :...
, carrying a copy of the Z Plan, was traveling the same itinerary in a separate plane. This second plane crashed near Cebu Island
Cebu Island
Cebu is an island of the Philippines. It is the main island of Cebu Province at the center of the Visayan Islands, south of Manila.It lies to the east of Negros Island; to the east is Leyte and to the southeast is Bohol Island. It is flanked on both sides by the Cebu Strait and Tañon Strait...
after attempting to avoid the same storm. Fukudome and nine others eventually made it to shore, where they were captured by local Filipino guerrillas who were supportive of the U.S. forces.
Because of the loss of the two planes, with their high-level occupants and important documents (Japanese ocean-current experts believed documents would eventually wash-up on shore), the Japanese applied intensive pressure on the local population. Partially as a result of this pressure, Fukudome and the others were eventually released.
On April 3, a wooden box from Fukudome's plane washed up near shore, and was secretly recovered by two villagers. The box contained the Z plan, a bound document in a red leather portfolio, with a Z on the cover. The documents eventually made it into the hands of the local guerrilla organization, the Cebu Area Command, under Lt. Col. James M. Cushing. The ornate nature of the documents led the CAC and their American handlers to suspect the documents were very important, a suspicion that was later reinforced by Japan's offer of a large reward for the return of any documents.
A clandestine high-priority submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
pickup was arranged, with a cover story
Cover story
Cover story may refer to:* a story in a magazine whose subject matter appears on its front cover* a fictitious account that is intended to hide one's real motive, e.g. when a terrorist pretends to be farmer to buy fertilizer or to provide an explanation in case it is found; the story in the case of...
of evacuating American refugees. The submarine picked up the documents, along with 40 American men, women and children. Traveling mostly on the surface for speed, and diving only when needed, the submarine survived depth charging twice, arriving near the American naval base in Darwin, Australia on May 19. From there the documents were flown to Brisbane.
The Z Plan documents were in plain text
Plain text
In computing, plain text is the contents of an ordinary sequential file readable as textual material without much processing, usually opposed to formatted text....
, rather than code, and were translated on an urgent basis by the top five translators at the Military Intelligence Service
Military Intelligence Service (United States)
The Military Intelligence Service was a World War II U.S. military unit consisting of two branches, the Japanese American Unit described here and the German-Austrian Unit based at Camp Ritchie, described partly in Ritchie Boys. The unit described here was primarily composed of Japanese-American...
attached to the Allied Translator and Interpreter Section
Allied Translator and Interpreter Section
The Allied Translator and Interpreter Section , also known as the Allied Translator and Interpreter Service or Allied Translator and Intelligence Service, was a joint Australian/American World War II intelligence agency which served as a centralized allied intelligence unit for the translation of...
, it was first translated by Yoshikazu Yamada and George "Sankey" Yamashiro, two nisei
Nisei
During the early years of World War II, Japanese Americans were forcibly relocated from their homes in the Pacific coast states because military leaders and public opinion combined to fan unproven fears of sabotage...
translators. Copies of the translation were rushed to General Douglas MacArthur
Douglas MacArthur
General of the Army Douglas MacArthur was an American general and field marshal of the Philippine Army. He was a Chief of Staff of the United States Army during the 1930s and played a prominent role in the Pacific theater during World War II. He received the Medal of Honor for his service in the...
, who quickly forwarded them to Admiral Chester Nimitz
Chester Nimitz
Fleet Admiral Chester William Nimitz, GCB, USN was a five-star admiral in the United States Navy. He held the dual command of Commander in Chief, United States Pacific Fleet , for U.S. naval forces and Commander in Chief, Pacific Ocean Areas , for U.S...
, commander in chief of the Pacific Fleet (and Admiral Kogo's counterpart). Among other things, planned Japanese diversionary tactics were now anticipated by the Americans, leading to the lopsided American victory in the Battle of the Philippine Sea
Battle of the Philippine Sea
The Battle of the Philippine Sea was a decisive naval battle of World War II which effectively eliminated the Imperial Japanese Navy's ability to conduct large-scale carrier actions. It took place during the United States' amphibious invasion of the Mariana Islands during the Pacific War...
, the largest aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
battle in history, and one of the decisive battles of the Pacific war.