Blacklist Operation Field Order No. 31 Headquarters I Corps

Planning for the American occupation of Japan after World War II.

“United States Forces in the Pacific, subsequent to the sudden collapse or surrender of the Japanese Government and Imperial High Command, will occupy JAPAN (exclusive of KARAFUTO) and KOREA (South of 38 degrees North latitude), establish control of Japanese Armed Forces and civil population, and impose thereon those prescribed terms of surrender requiring immediate military action.” – pg. 1

Operation Blacklist was the comprehensive Allied (largely American) plan for the post-war occupation and administration of Japan and its territories in the event of surrender or a government collapse. Its scope was vast and included strict social, industrial, and economic control over major urban areas, the demilitarization of the armed forces, and an extensive overhaul of Japanese political systems. Planning began (as ordered by General MacArthur) in May 1945 in conjunction with an alternate plan, Operation Olympic, should the enemy continue to resist.

The dropping of two atomic bombs and subsequent surrender of the Japanese government on September 2nd prevented the need for Operation Olympic and Blacklist was implemented. This rare set of Field Orders, issued to the headquarters of I Corps, was printed about a week after the surrender and provides fascinating insight into the campaign, set to start on September 25th (K-Day). Operating as part of the Sixth Army, the corps was assigned to land in the Osaka-Kyoto-Kobe region in Phase 1, followed by occupation duty around Nagoya in Phase 2. Elements of the force include the 33rd, 98th, 25th, and 6th Infantry Divisions, plus several specialized support units.

The contents of the field order (dated September 9th) outline many of the procedural hurdles faced by the victorious forces of the I Corps. Numerous annexes (essentially appendices), marked SECRET throughout, provide detailed instructions on sensitive topics including Chemical Warfare Intelligence Procedure, Summaries of the Enemy Situation and Order of Battle, Troop Loading and Landing Schedules, Signal Orders, Troop Lists, and Terms of Surrender and the Demobilization of Japanese Armed Forces. Long lists of enemy units reflect extensive forthcoming demilitarization efforts, while information on road signs, hospital layouts, and intelligence-gathering highlight an extended period of operational activity. Four maps are included:

• [Operations Overlay of Central Japan] –  A fascinating plan that appears to have been designed for use as an overlay for 1:250,000 scale maps of Central Japan. Labels Kyoto, Yokkaichi, and Nagoya, along with a simple route from M-Day.
• Chosen – Honshu – Reprinted by the 650th Engineer Battalion in August 1945, with later overprinting denoting enemy strength & dispositions across the I Corps Area.
• Operations Map – A map of southern Japan, dated September 9th, that has been overlaid with the major operations of the Sixth Army, with Centers of Occupation shaded.
• Western Japan – Reproduced by the 67th Engineer Topo Co. and dated September 12, 1945. A simple outline map of Western Japan that shows the Zones of Responsibility within the I Corps, sandwiched between the Eighth Army and the X Corps.

A distribution list in the collection indicates that sixty-six copies were printed and given to various elements of the Corps – only seven to each of the infantry divisions. As a result, the orders (even incomplete) are scarce survivors – I have been able to locate only one other copy of Operation Blacklist Field Order #31, in the Official Records of the I Corps Adjutant General’s Office. A similar field report, issued to members of the 6th Infantry Division (part of I Corps) can be viewed online at the Ike Skelton Combined Arms Research Library.

Further Reading: Ike Skelton Combined Arms Research Library; Marines in World War II (National Park Service); Basic Outline Plan of Blacklist; U.S. Army Center of Military History; Warfare History Network;