Top Secret Field Order Copy No. 3 [Operation Olympic – Japan]

Planning for the American destruction of Japan at the end of World War II.

“United States Army and Navy Forces, Pacific, invade Kyushu in order to intensify the blockade and aerial bombardment of Japan; contain and destroy major enemy forces; and support further advances for the purpose of establishing the conditions favorable to the decisive invasion of the industrial heart of Japan.” – pg. 1

In the late summer of 1945, it was becoming increasingly evident to the Allied powers that Japanese chances for victory in the Pacific were hopeless. However, the vicious battles for Iwo Jima and Okinawa earlier in the year gave American military leaders serious concern about the potential costs of invading the Japanese home islands to force a surrender. Planning for just such an event began in May 1945 and resulted in Operation Downfall. The first phase, Operation Olympic, involved a November 1945 assault on the southern portion of the island of Kyushu. This was to be followed by Operation Coronet, the invasion of Honshu, in early 1946.

This rare set of field orders pertaining to Operation Olympic (‘for tentative planning purposes’) consists of 130 typewritten pages stapled into over a dozen different annexes, or appendices. According to the front cover, the Top Secret orders were directed to the headquarters of I Corps, one of four corps that comprised the Sixth U.S. Army. The contents, dated between August 4th and August 12th, were mostly compiled by Brigadier General J.T. Murray, Chief of Staff for Major General Innis P. Swift, the oldest corps commander to serve in World War II.

The orders provide detailed instructions for the forthcoming invasion of Kyushu, which was to be divided into a preliminary phase followed by four primary phases. Information on objectives, paths of attack, and probable areas of resistance are provided for different corps elements across each phase. Lists of assigned units and their respective strengths, landing schedules, tables of sunrise/sunset times and tide levels, chemical warfare protocols, terrain studies, and POW/captured documents policies are included. Special attention is given to the prompt rehabilitation of transportation infrastructure (roads and airfields) and communication networks.

Four folding maps are present – most notably a large map of Kyushu, marked TOP SECRET, that notes estimated enemy strengths and dispositions as of July 21, 1945 with purple overprinting. Combat, base, and service troops numbers are distinguished from one another, though the A schematic diagram of Wakayama Beach is also included, along with two plans of the invasion beaches of differing scales. Also of interest are four appendices that present the organization of the Corps’ radio nets.

On X-Day, I Corps was scheduled to land in the Yamazaki-Matsusaki area in southeastern Kyushu, protecting the flank of the Sixth Army and eventually linking up with XI Corps. They were facing as many as 65,000 defenders across the area of operation, out of as many as 420,000 on the entire island. Fortunately for the members of the corps (and the Japanese populace), Operation Olympic was ultimately unnecessary. The dropping of atomic bombs on August 6th and August 9th compelled the Japanese leadership to sue for peace. As a result, the alternate Operation Blacklist was implemented – the peaceful occupation of Japan and subsequent political, economic, and social reorganization of the country. There is a perceptible change in the tone of the text between the earliest printed dates (August 4th) and the latest (August 12th), likely reflecting the changed geopolitical circumstances. The excerpt above is taken from the former, while below is taken from the latter.

“Going into the fourth quarter of her fourth year of the war with the UNITED STATES, JAPAN finds herself almost entirely cut off from her recently acquired empire to the south and west…To the Jap, the invasion of the homeland islands is now a certainty, the time and place only remains a question.”

While the front cover (written in manuscript) indicates this is Field Order Copy No. 3, several handwritten annotations throughout note it as copy number 33. A memo at the beginning of the volume instructs that all preceding copies were to be destroyed. The printed Distribution List, normally indicating the number of orders circulated to each unit (5-10/division), simply says “SPECIAL” – likely reflecting serious scarcity and restrictive access. I’ve been unable to locate other examples of the I Corps Operation Olympic Field Order, though it’s possible an unindexed version exists in The Official Records of the I Corps Adjutant General’s Office. A similar order, issued to the HQ of IX Corps, can be seen at the Ike Skelton Combined Arms Digital Research Library.

Sources/Further Reading: Ike Skelton Combined Arms Digital Research Library; Encyclopedia Britannica; Imperial War Museums; National WWII Museum;