How MacArthur Was Going to Invade Japan

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In 1966, two years after the death of Gen. Douglas MacArthur, the U.S. Army published the Reports of General MacArthur. Compiled by MacArthur’s staff, headed by Maj. Gen. Charles Willoughby and with the assistance of Prof. Gordon W. Prange, who was on leave from the University of Maryland, the Reports detailed the operations of forces under MacArthur’s command in the southwest Pacific, and included a chapter on “Operation Downfall,” the planned invasion of Japan.

In announcing their publication, Gen. Harold K. Johnson, then Chief of Staff of the U.S. Army, described them as “an illuminating record of momentous events influenced in large measure by a distinguished American soldier.”

The planning for Operation Downfall began in early 1945 at the Argonaut Conference in Malta, where the Combined Chiefs of Staff with the approval of President Roosevelt and Prime Minister Churchill set forth the following objectives for the Pacific War:

Following the Okinawa operation, to seize additional positions to intensify the blockade air bombardment of Japan in order to create a situation favorable to: An assault on Kyushu for the purpose of further reducing Japanese capabilities by containing and destroying major enemy forces and further intensifying the blockade and air bombardment in order to establish a tactical condition favorable to the decisive invasion of the industrial heart of Japan through the Tokyo Plain.

In March 1945, the U.S. Joint Chiefs of Staff, assuming that Germany would be defeated by early July 1945, divided Downfall into two main operations: Olympic, the assault on Kyushu scheduled for Dec. 1, 1945; and Coronet, the invasion of Honshu scheduled for March 1, 1946.  On April 3, 1945, the Joint Chiefs instructed MacArthur, in coordination with Adm. Chester Nimitz and Gen. Hap Arnold, to begin planning for the invasion of Japan.

MacArthur suggested to General George Marshall three approaches to bringing about the surrender of Japan:

First, the Allies could encircle Japan by further ... expansion to the westward, at the same time deploying maximum air power preparatory to attacks on either Kyushu or Honshu in succession, or on Honshu only. A second course would be to isolate Japan completely by seizing bases to the west and endeavoring to bomb her into submission without actually landing in force on the Homeland beaches. The third course open was to attack Kyushu directly and install air forces to cover a decisive assault against the principal island of Honshu.

MacArthur explained the advantages and disadvantages of all three strategies, and concluded that the third option would be the most effective in terms of attaining the objective timely and at reasonable cost. “[I]t ... would,” said MacArthur, “permit application of full power of our combined resources, ground, naval, and air, on the decisive objective.” Nimitz, according to the Reports, suggested several modifications but in general agreed with MacArthur’s plan, and both MacArthur and Nimitz advised Marshall to advance the date of the invasion of Kyushu to Nov. 1, 1945. After V-E Day in May 1945, the Joint Chiefs issued the directive for Olympic, giving MacArthur principal command of the invasion forces and setting Nov. 1 as the date for the assault on Kyushu.

The plans for Downfall assumed that Japan would vigorously defend its main islands with both military forces and “a fierce and active resistance by the entire population.” It was further anticipated that “massed Kamikaze attacks” would be launched against the invading American forces.

The Reports noted that the Japanese High Command in April 1945 issued its planned defense of the main islands, designated “Ketsu Operation.” The Homeland defenses consisted of “30 line-combat divisions, 24 coastal-combat divisions, and 23 independent mixed brigades, 2 armored divisions, 7 tank brigades, and 3 infantry brigades.” In addition, 8,000 “suicide or special- attack planes” and special attack boats and midget submarines were produced.

The planned U.S. invasion of Kyushu would be preceded by “one of the heaviest neutralization bombardments by naval and air forces ever carried out in the Pacific.” B-29 bombers would pound Kyushu from the air, while carrier task forces conducted coastal raids to attack Japan’s air and naval forces and to disrupt enemy communications. The last 10 days leading up to the landing “would see the massed bombing power of all available planes, both land and carrier-based, directed in a mighty assault to reduce the enemy’s defenses ...” The staging areas for the assault would be Hawaii, the Marianas, the Philippines, and the Ryukus. It was hoped that, as in the D-Day landings in Normandy, deception operations would be able to confuse Japan’s military and political leaders as to the precise locations of the assaults.

Operation Coronet would be launched four months after Olympic, and would utilize airfields on Kyushu to contribute to the invasion of Honshu. The goal was to destroy all opposition forces on the Kanto Plain and seize and occupy the Tokyo-Yokohama area. MacArthur planned to use the First and Eighth Armies, consisting of 10 infantry divisions, along with three marine divisions and two armored divisions, to make the initial assault. After seizing the Kanto Plain, the armies would be reinforced by 10 more divisions. As in Olympic, the Coronet assault would be preceded by bombardment by air and naval forces. “The total defeat of Japan’s armies in the core of the Empire,” the Reports note, “was the overall primary objective.”

U.S. plans assumed that Japanese forces would fiercely contest the landings, waging “an all-out battle on the main beaches leading to the Kanto Plain.” Tokyo also had plans to construct underground fortifications from which to conduct resistance for months or even years. “Whether or not these desperate but extensive defense measures would have made an invasion prohibitively expensive in American lives is a matter for speculation,” noted the Reports.

The atomic bombing of Hiroshima on Aug. 6, 1945, and of Nagasaki three days later, along with the Soviet declaration of war and invasion of Manchuria, and the subsequent Japanese surrender, meant that Operation Downfall — amphibious assaults that would have dwarfed the D-Day Normandy landings in scope and casualties — did not have to be undertaken. 

Interestingly, MacArthur, even before he knew about the atomic bomb, thought that an invasion of Japan would not be necessary. He told one member of his staff, “Don’t spend too much time planning for Olympic and Coronet. If you can find a way to drag your feet, do so, because we are never going to have to invade Japan.” According to MacArthur biographer Geoffrey Perret, once Macarthur was briefed on the development of the atomic bomb, he “was certain the bomb would knock Japan out of the war.” But he also believed and stated on several occasions, according to D. Clayton James, that “the use of atomic bombs at that stage was completely unnecessary from a military point of view to compel Japan’s capitulation.” That belief continues to be the subject of debates.

The Reports of General MacArthur concluded that it “is reasonable to assume ... that Operation Downfall could have been successfully concluded only after a hard and bitter struggle with no quarter asked or given. It was fortunate for both sides that Japan realized the wisdom of surrender and that the Allied plan eventually executed was not ‘Downfall’ but ‘Blacklist’ — a peaceful occupation without gunfire, without further destruction, and without bloodshed.”

In formally accepting the Japanese surrender on the U.S. battleship Missouri in Tokyo Bay, on Sept. 2, 1945, MacArthur expressed the sentiments of millions when he stated, “It is my earnest hope and indeed the hope of all mankind that from this solemn occasion a better world shall emerge out of the blood and carnage of the past — a world founded upon faith and understanding — a world dedicated to the dignity of man and the fulfillment of his most cherished wish — for freedom, tolerance and justice. ... Let us pray that peace be now restored to the world and that God will preserve it always.”

Francis P. Sempa is the author of "Geopolitics: From the Cold War to the 21st Century, America’s Global Role: Essays and Reviews on National Security, Geopolitics and War," and "Somewhere in France, Somewhere in Germany: A Combat Soldier’s Journey through the Second World War." He has written on historical topics, including the Civil War, for The Washington Times, The Diplomat, Orbis (the journal of the Foreign Policy Research Institute), the University Bookman, Presidential Studies Quarterly, and other publications.

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