1945 U.S. Army Information Branch Map of Japan and the Planned Amphibious Invasion

This is a rare Overseas Edition Newsmap published in October 1945 (1 month after the Japanese surrender) illustrating the planned amphibious invasions of the Japanese home islands.

A Closer Look

Three of the Japanese home islands appear here (Honshu, Shikoku, and Kyushu). Large white arrows illustrate Operation Olympic and Operation Coronet. The arrows for Operation Olympic mark approximately where American divisions would assault southern Kyushu with ten divisions landing on Kyushu and another three would act as a feint and floating reserve. Text along the right side provides a short summary of both operations and some of the units involved.

Operation Downfall

Operation Downfall was the codename given to the final assault on Japan. This plan was divided into two separate amphibious landings. Operation Olympic was set for November 1, 1945, and would invade southern Kyushu. Operation Coronet was scheduled to take place on March 1, 1946, and would invade Honshu at the Tokyo Plain. Plans for Operation Olympic stated that 582,560 troops would be landed on the first day and be spread over 35 invasion beaches. (For comparison, Operation Overlord, the invasion of Normandy, included almost 160,000 troops and nearly 7,000 ships and is the largest amphibious invasion in history.) U.S. military casualty estimates continued to mount throughout 1945, with experiences on Iwo Jima and Okinawa guiding these changes in understanding. U.S. casualty estimates vary wildly, but by late July 1945 the War Department estimated that Operation Downfall would cause between 1.7 and 4 million casualties, with between 400,000 and 800,000 Americans killed. The War Department Japanese casualty estimates in late July 1945 were that between 5 million and 10 million Japanese would be killed. These accuracy of these numbers (and the fact that there is so much variation in the estimates) play a part in the ongoing debate about the use of the atomic bombs. While we will never know what the numbers would have been, it is clear that an invasion of Japan would have been catastrophic for both sides.

Japanese Defense Plans

While this map focuses only on planned American operations, any discussion of Operation Downfall should also include Japan's defensive plans, called Operation Ketsugo, or Decisive Operation. It is clear from Japanese records that Japan did not plan to hold anything back for the defense of Tokyo. Their goal was to thwart the American invasion of Kyushu at almost all costs. All their aircraft and naval vessels would be committed to the defense of Kyushu (which they had correctly guessed would be the location of the upcoming invasion). They had also sent 900,000 soldiers to occupy Kyushu and repel the invasion, which far exceeded U.S. military estimates of Japanese defensive strength. (American plans called for the initial assault to comprise 582,500 men (as stated above) and for the total occupation force to top out at 766,700). The Japanese also planned to use everything in their arsenal to attack American troop ships and landing craft. Their main strategy was to cause as many American casualties as possible to make the stated objective of unconditional surrender politically impossible. The last and perhaps most devastating aspect of the Japanese plan was to not evacuate the civilian population. Japanese civilians had been barraged with propaganda since the early 1930s, conditioning the populace to believe certain things and think certain ways. In the summer of 1945, one of these propaganda slogans stated, 'The sooner the Americans come, the better…100 million die proudly'. With this strategy, not only would the invading American army be fighting the Japanese military, but also the civilian population. For more information on Operation Downfall we highly recommend the Naval History and Heritage Command's history. (https://www.history.navy.mil/about-us/leadership/director/directors-corner/h-grams/h-gram-057/h-057-1.html)

Publication History and Census

This map was prepared by the Information-Education Section of AFMIDPAC (Armed Forces Middle Pacific) and lithographed by the MIDPAC Army Print Shop. Overseas editions of Newsmaps like the present example were significantly smaller than the domestic editions distributed to armed forces installations across the United States. This is the only known cataloged example of the Overseas Edition of this Newsmap. The OCLC catalogs 7 examples of the domestic edition in libraries across the United States.