Talking Proud --- Military

Operation Downfall: The Planned Invasion of Japan

A lot of people these days talk about ending the war in Iraq, as though these things can be done "just like that." No one knew how to end the war with Japan in 1945, no one. At a top level, there were three options. Invade. Employ atomic weapons, more than two. Occupy immediately should Japan collapse internally or surrender by surprise. There was also a combo scenario to employ many atomic weapons and invade, either separately, or at the same time. The invasion was set and it was a "Go." Units were identified, many were training. We'll discuss the three options, and provide relevant background.

"How to" end the war against Japan: Invasion or A-bombs, or both?

By Ed Marek, editor

December 10, 2007, republished January 16, 2016


This is a photo of the Potsdam Conference, in Germany, on July 17, 1945, from the Truman Library. The participants were Britain, the Soviet Union and the Soviet Union. The purpose was to determined how to administer the defeated Germany, which had surrendered unconditionally on May 8, 1945. As an item left to last, the conferees issued an ultimatum to Japan to surrender unconditionally, or face complete destruction.

In truth, no one at the table knew how to end the war against Japan. No one knew what it would take to get the Japanese to surrender unconditionally.

Just a day before this conference began, on July 16, 1945, the Trinity Test of the Atomic bomb, the first and only test prior to operational employment, succeeded. Four days after the conference began, on July 21, 1945, President Truman formally approved the use of the A-bomb against Japan and three days later, on July 24, 1945, he approved the invasion of Japan's Home Islands in an effort called "Operation Downfall." Also in the bag of options was "Operation Blacklist" which was a plan to occupy Japan on very short notice should the government there and the state suddenly collapse or should the government suddenly surrender unconditionally.

One US military veteran said this:

"Wearing my Air Force T-shirt, I met a WWII vet in the grocery store, introduced myself, shook his hand, thanked him for his service, and asked where he served. He replied, Southwest Pacific, island hopping, ended up in Guam. In Guam, he trained to invade Japan. Looking at my T-shirt, he then smiled broadly, as did his wife, and said, "But you Air Corps boys took care of that. We didn't have to go. Thank you!"

I have thought a great deal about this veteran. His comment seems to make perfect sense. I think it is the widespread belief that the two atomic bombs dropped on Japan did it: they ended the war in the Pacific.

But I'm not so sure ending the Pacific War came that easily. The Allies delivered a lot of knockout punches to the Japanese, they had a lot more to deliver, but still it took them a very long time before they threw in the towel.

If there was a single event that ended the war, it was when Emperor Hirohito delivered his radio speech on August 15, 1945. That's when he called it a day. He told his people this:

"I have ordered the Imperial Government to inform the four Governments of the United States, Great Britain, China and the Soviet Union that our Empire is willing to accept the provisions of their Joint Declaration."

The "Joint Declaration" was the Potsdam Declaration, which demanded the unconditional surrender of Japan. He refused to say the words unconditional surrender publicly; he even refused to use the word surrender. So even with his radio speech there was skepticism and uncertainty.


Hirohito surveys bomb damage in Tokyo, August 1945. Presented by WWII Multimedia Database

The US dropped the first A-bomb on Hiroshima on August 6, 1945, the second on Nagasaki on August 9. In no mood to miss out on the spoils of war, the Soviets declared war in Japan on August 8 and invaded Manchuria. The Allies had hoped surely that would be enough.

It was not enough. It took six days of grueling debate in Japan's inner circles of power, and one thwarted coup attempt, before the emperor took to the microphone. It then took until September 2, 1945 for Japan to sign the formal documents. During the intervening period, the Soviets continued their march through Manchuria, and US forces prepared to occupy Japan, taking every precaution to avoid being trapped and fooled. There was an attitude of uncertainty about what might happen for some time, even into the occupation.

We might commend an article we did on October 16, 2005, "Peacekeeper, a brave and able warrior, is retired," the section, "The 20th Air Force, bombers over Japan to hot missiles ready to go, World War II Days." It provides some good background on the final days.

The Japanese never thought they could defeat the US militarily. Some boasted they would conquer the US, but there was no serious thought given to such an endeavor. Instead, the Japanese wanted to force a negotiated settlement with the US that would award many or all of its Pacific holdings to the Japanese. That would make Japan a global economic and military power worthy of great respect in any king's court.

Japanese Admiral Isoroku Yamamoto, shown here, the man who led the attack on Pearl Harbor, is quoted saying it this way on a number of occasions to members of the Cabinet in Japan in 1940:

"I can run wild for six months (after Pearl Harbor), after that, I have no expectation of success."

The Japanese strategy to seek a negotiated settlement had a fundamental flaw. Once the Japanese advance took full throttle and the attack on Hawaii came on December 7, 1941, the term "negotiated settlement" left the American lexicon. Yes, it was discussed, but not seriously. The US wanted complete victory and an unconditional surrender.

The Allied strategy in WWII at its top-level was to defeat Germany first and obtain an unconditional surrender there, then defeat Japan and obtain an unconditional surrender there.

DonitzKarl JodlAlfred

Admiral Karl Donitz General Alred Jodl

But getting an unconditional surrender from Germany was no "slam dunk" either. Hitler was dead, Admiral Karl Donitz became the Führer. General Alfred Jodl was the Chief of the Operations Staff of the Armed Forces High Command, second to General Wilhelm Keitel, Germany's senior military leader.

Donitz appointed Jodl to negotiate with the Allies. Donitz directed Jodl to play around for time, so as many German troops as possible could out of the Soviet zone and into the western zone. General Eisenhower, the Allied Supreme Command, refused to deal with Jodl. Eisenhower grew impatient, and, through his own representative, ordered Jodl to surrender unconditionally or face a western blockade that would prevent his troops from escaping from Soviet lines. With approval from Donitz, Jodl followed Ike's order. The Allies had done everything they could to make sure the Germans could not reconstitute in the Austrian Alps at a location known as the "National Redoubt." The point we wish to make is that the Allies had virtually destroyed Germany. There were very few targets left. Yet, uncertainties remained.


USS West Virginia struck at Pearl Harbor.

In the case of Japan, their high point was December 7-8, 1941, when they attacked Pearl Harbor and invaded the Philippines.


Douglas Dauntless shipborne dive bombers during the attack on the Japanese fleet off Midway, June 4 to June 6, 1942. Presented by the National Park Service.

Just six months later, as Yamamoto had predicted, the US fleet and Army Air Force soundly defeated the Japanese fleet at Midway. From that point on, the Japanese were on the defensive and the Americans and their Allies were on the offensive. From this point on, the best the Japanese could hope for was to prolong the war, make it as costly to the US and her allies as possible, and force the US to a negotiated settlement favorable to Japan. In short, Japan would fight a war of attrition. The Japanese were very successful doing this. The war lasted just over four more years.

Right up to the very end, the Japanese military leadership was prepared to expend all souls under its command and all souls of its citizens to force a negotiated settlement. The US was prepared to take on that challenge and invade Japan until an unconditional surrender were obtained. That plan was known as "Operation Downfall." In turn, the Japanese prepared for the invasion and many Japanese military leaders felt they could defeat the invasion and inflict so many American casualties that the US would be forced into a negotiated settlement.

American ground forces invaded Guadalcanal in the distant Solomons Islands near Australia on August 7, 1942. This was the first major US ground offensive in the war and the first major amphibious landing by the US Marines in their history. From this victory onward, the US took the offensive, US forces marching, flying and sailing up Admiral Nimitz's chain of islands to Okinawa and doing the same through General MacArthur's chain of islands that included New Guinea and the Philippines to Okinawa.


On April 1, 1945, all these American forces and more converged on Okinawa in arguably the most fierce battle of the war. It lasted through June 1945. The Americans prevailed in victory. The Allies were now about 320 miles from Japan's Home Islands.


B-29 "Superfortress," presented by Boeing.

General Henry "Hap" Arnold's B-29 long range bombers were hammering the Home Islands daily from islands in the Marianas won by the blood and sacrifice of many American forces. With Iwo Jima in American hands, these bombers picked up a fighter escort from Iwo Jima to their targets on the Home Islands and back. Furthermore, Iwo Jima gave the bombers an emergency base. Indeed, the first B-29 to make an emergency landing at Iwo Jima, "Dinah Might," landed during the heat of fighting.


Yokohama ablaze from a B-29 incendiary bombing attack. Yokohama Yokohama is on the peninsula facing the western coast of Tokyo Bay, and served as a main port facility for Tokyo. Presented by Air Raid against Cities of Kawasaki and Yokohama

The realization dawned on the military leadership that most of Japan was built from wood, making the entire country vulnerable to incendiary bombing. The American incendiary bombing campaign showed little mercy. Cities were burned to the ground.


The aftermath of the US fire bomb raid on Tokyo, March 10th, 1945. Presented by Japan Nihon Livedoor Blog.

While it was obvious to most that the US was inflicting enormous damage on the Japanese, the reality was that US military and civilian leaders did not know what it would take to cause Japan to surrender unconditionally. Privately to be sure, many acknowledged this. Our forces in the Pacific saw it the same way.

Most military leaders believed they would have to invade, even if the A-bombs were employed. No one really knew what the A-bomb would do once employed. Some were not sure they would work. Some did not believe the Japanese would surrender even if these bombs were used. Once dropped, most of our fighting forces thought the war would end, but they were not really sure. Even if the war did end, they knew they would have to go in as an occupation force, and no one knew how that would be received by the Japanese.

There were so many uncertainties about what it would take for the Japanese to surrender unconditionally that the American leadership had to whittle down the possibilities simply to assemble plausible plans. They whittled them down to three.

The one favored the most by senior military commanders and cabinet secretaries was to invade Japan's Home islands. That was Operation Downfall.

A contingency plan, dubbed "Blacklist," was developed to respond to a sudden and unexpected collapse of the Japanese government or a sudden and unexpected agreement to surrender unconditionally. In either case, the US would have to move considerable occupation forces into Japan's Home Islands and do so promptly. There was a lot in common between Downfall and Blacklist.

Finally, there was the plan to drop as many as two newly developed Atomic bombs on specified targets on the Japanese Home Islands, and then wait to see what happens. If required, they could drop follow-on A-bombs coming off the line over the next months until the Japanese gave in. If the Japanese would still not give in, then the invasion would have to go ahead and more A-bombs coming off the line could be employed tactically.

By the summer of 1945, Downfall and Blacklist were both "doable." But many uncertainties still surrounded the A-bomb.

The Japanese leadership understood well that invasion was now not only possible, but probable. They had been bringing home their very best ground units from the Asian mainland to face this eventuality. Many top Japanese leaders, especially in the military, felt they could defeat an American invasion. We do not think these men knew about the A-bomb.

So, here we are. It's summer 1945, the US and its Allies are 320 miles away from Japan's Home Islands, Japan is in a shambles, getting worse every day, but both sides were gearing up for invasion, a fight that had every chance of being the bloodiest in human history.

What is fascinating here is that no one knew how to end the Pacific war. The Japanese still thought they could rig up a negotiated settlement, through the Soviets, but the Soviets had already double-crossed them and were preparing to invade

Manchuria and declare war against Japan in a deal made with the Americans. There were calls in the US to agree to conditions, at least a condition that would leave the emperor in place and on the throne. But the leadership would not agree to such a condition publicly.

I'm going to give you a very brief glimpse at the Downfall Plan, and, an even more brief look at Blacklist. I will follow that by summarizing the evolution of political events at home leading to Japan's ultimate unconditional surrender in September 1945. And then I want to take on a job that has slowed publication of this report for several months: try to put a human face on the force that would have had to invade had the invasion occurred.

Operation Downfall - The Invasion of Japan


Operation Downfall was the name given to the overall invasion of Japan. It would be the largest amphibious invasion in the history of warfare.

Operation Olympic was the name used for Phase 1, the invasion of the southern Kyushu Island. The landings were scheduled to begin on November 1, 1945. US ground warfare had largely stopped with the victory in Okinawa in June. US forces were dispersing throughout the Pacific to rest, resupply, regroup, and train for the invasion. Okinawa and the Philippines would be the main jump-off points for Operation Olympic. General MacArthur would command the invasion.

The 6th US Army, the "Alamo Force," motto, "Born of War," would lead the invasion. This Army was commanded by Lt. General Walter Krueger, who had fought in northern New Guinea, Leyte and Luzon. The 6th Army would employ three corps of nine divisions, three Marine, six Army, with others available if required. There is a lot of good documentation of the plan on the internet.

These are the units tapped to execute the Operation Olympic plan to invade Kyushu Island.

6th US Army - Operation Olympic, November 1, 1945

V Amphibious Corps - Target, southwestern Kyushu


Logos left-right:
2nd MARDIV, "Follow Me", Guadalcanal, Tarawa, Saipan, Okinawa
3rd MARDIV, "Fighting Third", Bougainville, Guam, Iwo Jima
5th MARDIV, "The Spearhead", Iwo Jima

XI Corps - Target, southern Kyushu

1stCavDivisionPatch 43rdInfDivPatch AmericalPatch

Logos left-right:
1st Cavalry Division, "Hell for Leather", Admiralty Islands, Leyte, Luzon
43rd Infantry Division, "Winged Victory Division", New Caledonia, Guadalcanal, Russell Islands, New Guinea, Lingayen Gulf, Luzon
Americal Division "Americal", Guadalcanal, Bougainville, Leyte

I Corps - Target, southeastern Kyushu

25thDivPatch 33rdDivPatch 41stInfDivPatch

Logos left-right:
25th Infantry Division, "Tropic Lightning", Guadalcanal, New Georgia, Luzon
33rd Infantry Division, "Winged Victory Division", New Guinea, Lingayen Gulf, Luzon
41st Infantry Division, "Jungleers", New Guinea, Philippines

IX Corps - Reserve Force

77thDivPatch 83rdDivPatch 98thDivPatch

Logos left-right:
98th Infantry Division, "Iroquois", Hawaii, no combat yet
77th Infantry Division, "Statue of Liberty Division", Guam, Leyte
83rd Infantry Division, "Thunderbolt Division", Normandy, Northern France, Rheinland, Ardennes-Alsace, Central Europe

Operation Coronet was the name used for Phase 2, the invasion of the Tokyo or Kanto Plain on Honshu and beyond. The 1st and 8th US Armies had the lead. The 10th Army would follow as reinforcement later if required. This invasion was scheduled to begin on March 1, 1946.

1stArmyPatch 8thArmyPatch

1st US Army and 8th US Army

As an aside, the political view in the US was that this war had to be over no later than the end of 1947. The feeling was the American people would not tolerate its continuation beyond then.


As best we can tell, specific units were not firmly identified for Operation Coronet. That said, we have seen this chart which does show a selection process had been hatched. It was known as the Provisional Order of Battle for invasion of Japan, August 1945.

Coronet would be supported by all army and naval forces in the Pacific and, in addition, would be augmented by combat units from Europe whose war, the troops thought, had just ended.

The 1st and 8th US Armies would employ 10 reinforced infantry divisions, three Marine divisions, and two armored divisions. As an aside, employment of these Marine three divisions meant that the entire US Marine Corps would be involved in the total invasion package, Phases 1 and 2.

Thirty days after the initial landings, each army would be reinforced by a corps of three divisions. Five days later, an airborne division and an Army Reserve Corps of three more divisions would be added. All together, this would be a 25 division force. These 25 divisions were to seize the Kanto Plain, including the general areas of Tokyo and Yokohama, and then carry out any additional operations necessary to break Japanese resistance. Strategic reserve for the entire operation would consist of a corps of three divisions located in the Philippines and a sufficient number of divisions from the United States to permit reinforcement at the rate of 4 per month.

The plan envisioned the complete destruction of the state of Japan if required.

Summary of Political Events to End the War

William Burr has edited "The Atomic Bomb and the End of World War II, a Collection of Primary Sources," presented by George Washington University as "National Security Archive Briefing Book No, 162." This is a fantastic resource to

understanding what was happening behind the scenes as people scurried about trying to end WWII in the Pacific.

We'll drop back momentarily to early 1945.

Our forces had just completed the successful invasion of Iwo Jima, fought from February through March 1945. The US military then invaded Okinawa starting on April 1, 1945, and finished up in late June.

These were among the most costly and fierce battles for Americans in any war. The Japanese lost over 20,000 killed on Iwo Jima. The Americans lost 6,825 killed and 27,909 total casualties. On Okinawa, the Japanese lost about 66,000 killed and 7,000 captured. The Americans suffered 12,513 killed or missing, and a total of about 72,000 casualties.


Franklin Delano Roosevelt's funeral procession with horse-drawn casket, Pennsylvania Ave.

On April 12, 1945, just shortly after the invasion of Okinawa began, President FDR died. While his health had obviously deteriorated, his death nonetheless came as a psychological shock to the nation and to American combat forces in the Pacific.


Vice President Harry Truman takes the oath of office as President of the United States, April 12, 1945.

Vice President Harry Truman was sworn in as president. Truman served in France during WWI as an artillery officer, and rose to the rank of major. This experience served him well in the months ahead. He was elected to the US Senate in 1934 and was a strong supporter of FDR's policies. History Central reported his ascendancy to the presidency this way:

"His brief period as Vice President was uneventful. Truman was having a drink in the office of Senate Speaker Sam Rayburn when he was summoned to the White House on April 12, 1945. Mrs. Eleanor Roosevelt greeted him with the words, 'Harry, the President is dead.' Truman replied, 'Is there anything I can do for you?' Mrs. Roosevelt shook her head and replied, 'Is there anything we can do for you? For you are the one in trouble now.'"

Just two weeks later, on April 25, Secretary of War Henry Stimson, shown here, briefed President Truman on the existence of the A-bomb project, the "Manhattan Project," and told him the target was Japan. Mr. Truman did not know about this project previously.

Stimson brought a memorandum signed by General L. R. Groves, the project manager, to discuss the bomb with the president. Stimson also brought his own talking paper. Both are presented by the National Security Archive.

  • Mr. Truman was told the first bomb would be ready by August 1, 1945, a second one before the end of the year, and succeeding ones about every 60 days thereafter.
  • A test would be conducted in July.
  • The target is Japan.
  • The 20th Air Force commanded by General Curtis Lemay has organized a composite group to train and equip for the attack.
  • Initial echelons would soon depart for an overseas destination to prepare for the drop.
  • Various aspects of the technology are known among scientists worldwide. It is probable that other nations will learn how to build these bombs. Russia will probably be the first to succeed.

Not only was he briefed about the project, he was told that target selection had begun. By the end of May, he was told that Kyoto (the ancient capital), Hiroshima, Kokura and Niigata were the targets.

At this same time, April 1945, planners in the Pentagon advised the Joint Chiefs of Staff (JCS) that they believed the Japanese would not accept an unconditional surrender unless they were given a loose definition of the word "unconditional." These analysts argued that any American threat to defeat the Japanese "absolutely" would not be enough to get them to surrender. They told the Chiefs that the only alternative that seemed workable would be annihilation of the Japanese state and most of its people.

On May 8, 1945, the war in Europe ended. This was very important to the Pacific war. FDR, Churchill and Stalin set the defeat of Germany in Europe as priority number one that had to be completed first. Then they could turn to ending the war against Japan.


A 1945 U.S. Army map showing the possible extent of the National Redoubt. Presented by

It's worth noting here yet again that obtaining an unconditional surrender from the Germans was no easy chore. The country was in ruins, the German military was virtually destroyed, but there were fears the German leadership would establish a significant military capability in what was called the National Redoubt in the Alps of Austria, and fight on from there. The Germans had already put a jet fighter into combat and there was no telling what else they might have in development. The word "Redoubt" is a term for an area to which remaining forces of a nation can be withdrawn if the main battle is lost, or even beforehand if defeat is considered to be inevitable. General George Patton had to divert his forces to block such an effort, and General Eisenhower asked Marshal Stalin to do the same. As it turns out, the idea of a Redoubt was more a German deception than a reality.

Nonetheless, it affected military decision-making. We earlier discussed that with Hitler dead, the German military leadership wanted to gain as much time as they could to get their forces out of Soviet territories, so the Germans were slow to accept an unconditional surrender.

This is one of many reasons the US military leadership worried so much about what it would take to get the Japanese to surrender unconditionally and helps explain why they favored invasion.

The A-bomb was a very secretive effort and did not enjoy much popularity among American military leaders. General Douglas MacArthur was told of plans to employ it against Japan. He was not impressed, saying this:

"In the mean time, I have a war to fight."

We'll talk more to this in a moment.

Victory in Okinawa by mid-May was almost assured. As a result, on May 25, 1945, JCS issued the execute order for Operation Downfall. The Chiefs directed General MacArthur, General Henry "Hap" Arnold and Admiral Chester Nimitz to implement Phase I of the invasion, Operation Olympic.

The JCS followed-up its execute order and submitted the Operation Downfall plan to President Truman in June 1945. President Truman received this plan at a time when the A-bomb had not yet even been tested.

In a diary entry of June 17, 1945, the president, in office for only two months and kept largely out of the war loop by FDR, noted what seemed to be his only two options: invade and blockade, or bomb and blockade. By "bomb" could be meant continued incendiary bombing of the islands and/or employment of the A-bomb.

With the invasion plan on his desk, President Truman called a meeting in the White House on June 18, 1945. At this meeting, the JCS, the secretaries of war and the Navy confirmed their opinion that the Kyushu Operation Olympic was the best solution. At meeting's end, the president said the Joint Chiefs should proceed with the Kyushu operation. The decision to issue an execute order had been validated. Downfall was a "Go."

On July 2, 1945, Secretary Stimson sent the president a memo which said this, among other things:

"The plans of operation (Downfall) up to and including the first landing have been authorized and the preparations for the operation are now actually going on."

We'll stop here and switch gears a bit.

In May 1945, some say even earlier, MacArthur's staff began planning for the occupation of Japan. The assumption underlying this plan was that it would be implemented once the Japanese had accepted the terms of an unconditional surrender. That said, it could also apply if there were a sudden implosion of the Japanese government that demanded a rapid occupation before things got out of hand. The plan that emerged in August was called "Operation Blacklist."

As an aside, General MacArthur, and many others, believed that the US needed to tell the Japanese that they could retain the institution of the emperor after their surrender. Some believed the term "unconditional surrender" could still be used, with private assurances that the emperor could remain. MacArthur for one believed that the war would end quickly if the US provided such an assurance. It is our understanding the US ended up providing such a private assurance, an argument which stands today in the minds of many as reason not to have dropped the two A-bombs.

Major James D. Brinson, USA, wrote a thesis on the subject of Operation Blacklist, "A study of postwar Japan (1945-1950)," in which he said:

"Well before the war ended, the US invested much time and resources to develop the plans and policies for administering Japan ... Over two thousand Army and Navy officers were trained by August of 1945 for duty in Japan as military and civil affairs specialists. The training centers established and civilian universities involved in this effort were significant.

"The extensive prior planning for postwar Japan had established initial policies for the occupation to implement.

"One of the policies for postwar Japan was to leave the Emperor in place after defeating the Japanese military. Another was to use the existing government structure as much as possible. Many of these policies were specified in the US Initial Post Surrender Policy for Japan which was transmitted by the State-War-Navy Coordination Committee to the US military leadership in the Pacific on 29 August 1945."

"Operation Blacklist" projected that the Japanese would accept an unconditional surrender (with the understanding that the institution of emperor would be left in tact) sometime between August 1 and October 15, 1945. General MacArthur would lead the occupation. The occupation would start with a series of landings by US Army and attached forces. The objectives were to occupy critical areas on the Home Islands and the Korean peninsula, gain control over Japan's military and the civilian population, and impose the terms of the unconditional surrender. Since no one knew the date of initiation of this plan, forces were to be ready to go on a moment's notice.

So two plans were on the table, Downfall and Blacklist. Both involved landing a considerable number of American forces landing on Japan's beaches, which by the way, were few and far between. For example, the US 6th Army was scheduled to invade Kyushu for Operation Downfall and was also scheduled to occupy Kyushu under Blacklist. Similarly, the US 8th Army, scheduled to invade Honshu for Downfall, was designated the occupying force for northern Japan. The 10th Army, which was to be a reinforcement for Operation Coronet, was designated to go to Korea. That was later changed to the XXIV Corps of the 10th Army. The US 1st Army, scheduled to invade Honshu for Downfall, was in Europe and for Blacklist was no longer needed.

So the situation for MacArthur was this. He and his staff were doing the bulk of Downfall and Blacklist planning, both plans were considered executable, and each had the president's approval. The A-bomb, on the other hand, was an unknown.

So let's address the A-bomb. The A-bomb was first tested on July 16, 1945 in New Mexico. That was known as the "Trinity Test." The test bomb was called the "Gadget." The Gadget worked in this test. But this test was an experiment. No one knew for sure what the results of the experiment might be. Betting pools were set up among the scientists.


The preparation of the "Gadget" for the Trinity test, July 1945. Presented by wikimedia commons.

Perhaps more important, the Gadget's components were raised by a pulley system to the top of a 20-meter tower for a final assembly there.


Setting up the "Gadget" for the Trinity test, 1945. Norris Bradbury is on the left. Presented by wikimedia commons.

The final assembly took some effort by specialized teams. The detonation was delayed because of weather. Some 45 seconds before detonation, a robot assembly took control and there was no human control of the concluding sequence of events. The method of detonation was "implosion" at the top of the tower caused by a spherical arrangement of explosive charges that would increase the density inside the sphere that would set off a nuclear explosion.

From a military perspective, especially after a long and brutal war in the Pacific, this was an experimental test from a tower that demanded a great deal of scientific intervention. This was not even close to being a test of a weapon dropped from an aircraft, much less a final test of a weapon that had passed muster and was ready to be operationally employed by a B-29. So, one can understand the military reluctance to try using it operationally at this stage of its development. Furthermore, the military and others, having seen what the bomb did do during its test, worried about the moral implications of the military being the first to use it in anger.

All that notwithstanding, Eleanor Roosevelt was right. It was President Truman who bore the burdens of this war on his shoulders. It was July 1945, Japan was largely in ruins, it had virtually no navy or air force, Okinawa was ours, and the Japanese have not surrendered. From Truman's vantage, the success of the Trinity presented another option to join with Downfall and Blacklist.

Truman's earlier diary note took form. He could employ the A-bomb or invade. If the Japanese surprised everyone with a sudden unconditional surrender, or if the government in Japan completely and suddenly collapsed, he could order a rapid occupation. He had three plans. As we will discuss in a moment, he had even another option: employ the A-bomb and invade.

President Truman formally approved the use of the A-bomb against Japan on July 21, 1945 and formally approved Operation Downfall on July 24, 1945. An atomic bomb attack against Japan and an invasion of Japan were now both a "Go." While these "Go" orders were real, the president would constantly and continuously revisit the options.

The appropriate flag officers already had their execute orders for Operation Downfall. On July 24, 1945, Secretary of War Stimson passed on the A-bomb order to General Thomas Handy, USA, the acting chief of staff. General Marshall, the chief of staff, was with President Truman at the Potsdam Conference with Churchill and Stalin, so the job of physically passing the "Go" order went to Handy.


A-bomb targets. The National Security Archives contain multiple memos to define the targets.

On July 25, General Handy, shown here, gave the A-bomb order to General Carl Spaatz, commander of the Army Air Force. The order was to attack Japan with the atomic bomb, the first weapon to be dropped on one of four possible targets: Hiroshima, Kokura, Niigata or Nagasaki; Kyoto, the ancient capital, had been removed from the target list, and Nagasaki added. The order read in part as follows:

"The 509th Composite Group, 20th Air Force will deliver its first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets: Hiroshima, Kokura, Niigata and Nagasaki ... Additional bombs will be delivered on the above targets as soon as made ready by the project staff. Further instructions will be issued concerning targets other then those listed above ... It is desired that you personally deliver one copy of this directive to General MacArthur and one copy to Admiral Nimitz for their information."

In sum, on the day that General Spaatz received his order to employ the A-bomb against Japan, the US military was working with two orders, this one, scheduled for late August, and the one to execute "Operation Downfall" on November 1, 1945. In addition, MacArthur had Operation Blacklist in his hip pocket should he have to quickly occupy Japan.

With regard to Downfall, D.M. Giangreco has written this:

"Construction of the massive prefabricated components of a portable harbor to support forces invading Honshu had a priority second only to the Manhattan Project which had produced the bomb. Stateside hospitals were readied for a flood of wounded."

On July 26, through the Potsdam Declaration, the US demanded Japan surrender unconditionally or face "prompt and utter destruction." As expected, on July 28, Japan publicly rejected the demands of the Potsdam Declaration. Japan's prime minister not only rejected it, but said this:

"We will do nothing but press on to the bitter end to bring about a successful completion of the war."

The US had earlier intercepted Japanese messages indicating that the Japanese were trying to use the good offices of the Soviets to bring about an end to the war.

That said, in an intercept of July 22, 1945, Japanese Foreign Minister Shigen Togo, shown here, issued clear direction on the matter of unconditional surrender:

"With regard to unconditional surrender, we are unable to consent to it under any circumstances whatever. Even if the war drags on and it becomes clear that it will take much more bloodshed, the whole country as one man will pit itself against the enemy in accordance with the Imperial Will so long as any enemy demands unconditional surrender."

This must have been a difficult message for Togo to issue. He was against the war from the outset, and was one of the main players in convincing the emperor to end it. At this point in time, Togo was hoping the Soviets could help them obtain a peace that at the least would keep the emperor in place. None of this worked.


Little Boy atomic bomb unit on trailer cradle in pit. Note bomb bay door in upper right-hand corner. August 1945. Presented by wikipedia.

The orders had gone out in July. Let the record affirm the first A-bomb, "Little Boy," was dropped by the 12-man crew of the B-29
Enola Gay, callsign "Dimples Eight Two," on Hiroshima on August 6, 1945. Colonel Paul Tibbets was the aircraft commander. It did not come as much of a surprise to his crew, but Tibbets told his crew for the first time they would be dropping the A-bomb on this mission.

This mission had been delayed several times for bad weather. At first, the 4th looked good, then the 5th, then the 6th.

Weather over the target was forecast as good for August 6. Takeoff was at 1645Z (2:45 am) August 5, 1945. Takeoff speed was 155 mph. In 10 minutes, over Saipan at 4,700 ft. Three hours later they were over Iwo Jima. About five hours after launch, Little Boy was armed. Dimples 82 climbed to 30,700 ft. A reconnaissance aircraft reported that cloud cover over Hiroshima was three-tenths. Tibbets informed his crew they would bomb Hiroshima. The target was a T-shaped bridge in Hiroshima. Six and one half hours after takeoff, Little Boy was dropped.

As soon as the bomb dropped out of the aircraft, the B-29 pitched because it had just gotten rid of 10,000 lbs. Tibbets went into a tight turn, levels out, everything is okay with the aircraft, and Tibbets wanted to get to the Sea of Japan as quickly as he could. The crew started filling out its logs, the shockwave was coming at them, and their equipment measured being hit by 2.5 Gs at 10.5 miles from the target.

A flash report was sent out from the Enola Gay following the drop:

"Results clearcut, successful in all respects. Visible effects greater than New Mexico test. Conditions normal in airplane following delivery."


Atomic cloud rises over Hiroshima. Photo taken from the B-29 Enola Gay about 30 seconds after the A-bomb exploded. Presented by Atomic Bomb Museum.

The aircrew reported the following:

"Target at Hiroshima attacked visually 1/10th cloud at 052315Z. No fighters. No flak."


At the White House, President Truman announces Japan's surrender. Photo credit: Abbie Rowe, Washington, DC, August 14, 1945. Presented by National Archives.

President Truman announced the attack. This is part of what he said:

"Sixteen hours ago an American airplane dropped one bomb on Hiroshima, an important Japanese Army base. That bomb had more power than 20,000 tons of T.N.T. It had more than two thousand times the blast power of the British 'Grand Slam' which is the largest bomb ever yet used in the history of warfare.

"The Japanese began the war from the air at Pearl Harbor. They have been repaid many fold. And the end is not yet ... We are now prepared to obliterate more rapidly and completely every productive enterprise the Japanese have above ground in any city. We shall destroy their docks, their factories, and their communications. Let there be no mistake; we shall completely destroy Japan's power to make war.

"... If they do not now accept our terms they may expect a rain of ruin from the air, the like of which has never been seen on this earth. Behind this air attack will follow sea and land forces in such numbers and power as they have not yet seen and with the fighting skill of which they are already well aware."


President Truman (center seated) announcing that Russia declared war on Japan, August 8, 1945. The man on the lower right smiling is Secretary of State James Byrnes. Presented by the Harry Truman Library.

On August 8, the Soviets turned on the Japanese, declared war against them, and marched into Japanese-occupied Manchuria, a surprise to the Japanese that such an invasion came so early. It turned out that the US and USSR had been in cahoots on a Soviet declaration of war against Japan, though, as you will see, one of the reasons Truman felt a need for speed to end the war had to do with his distrust of the Soviets.

To demonstrate how much uncertainty about how the war would end still existed as of August 8, Secretary of the Navy James Forrestal sent a memo directly to the president which said, among other things:

"It is my opinion that the matter of common direction and command for the final operations against Japan in the Pacific (Downfall) is still not satisfactorily settled ... I suggest that you give serious consideration to the selection of either General Marshall or General Eisenhower to assumed the over-all command."

Even though one A-bomb had been dropped, Forrestal was nonetheless focused on and worried about who would command the invasion of Japan.


The Fat Man bomb being readied on Tinian. Presented by Atomic Archive

On August 9, the crew of the B-29 Bockscar dropped the "Fat Man" A-bomb on Nagasaki. The mission was scheduled for August 11, but a typhoon forced a change to August 9.

Major Charles Sweeney, shown here, was the squadron commander and decided to go on this mission, making him the aircraft commander. Capt. Charles Don Albey was normally the pilot for this aircraft, but he moved over to the co-pilot's seat for the skipper. The mission callsign was "Dimples Seven Seven."

The mission encountered some problems. First, The B-29
Great Artiste was on the schedule to fly this mission. Sweeney, the squadron commander, had flown most often aboard Great Artiste. But she had been outfitted with gear compatible with the first mission, so the B-29 Bockscar was handed the mission, and was to be flown by the Great Artiste's crew. Technically, there was an aircraft familiarity issue.

Then there was a problem with the fuel transfer pumps. Tibbets told Sweeney he didn't need the extra 600 gallons in the reserve tank that could be transferred by these pumps. After a long discussion, Sweeney decided to launch.
Bockscar took off at 3:49 am with a crew of 11, plus some observers, an hour behind schedule. The bomb was armed about 30 minutes later, at 4:15 am.

The typhoon forced Sweeney to fly higher than desired, using more fuel than desired, and west of the route, forcing use of even more fuel than desired.

Next, one of the observation aircraft did not meet up with
Bockscar at the rendezvous point. He was orbiting about 9,000 feet above Bockscar "in the soup" at the rendezvous but the two never saw each other. Even though ordered to wait no longer than 15 minutes, Sweeney waited 40 minutes, and decided to go without the other aircraft. Sweeney decided to go to the first target on his list, Kokura.

Bockscar got to the target, but the bombardier could not see it because of smoke from firebombing the previous day. The crew attempted three runs at the target, but it was blocked by smoke each time. Bockscar was receiving anti-aircraft fire and some enemy fighters did get airborne. Sweeney then turned to the secondary target, Nagasaki.

Fuel was now an issue because of the time wasted going to and flying around Kokura. The skies had clouded up. Sweeney told the crew they would have only one run at the target, and he instructed the crew to go in on radar. This was against the rules, which required visual acquisition of the target, but all hands agreed to go in radar anyway. At the last moment, the bombardier said he had the target visually. The bomb was released at 11:58 am.


Nagasaki strike photo, August 9, 1945. Presented by The Hawai'i Nisei Story.

Sweeney immediately put his aircraft on a course to Okinawa rather than Tinian or the emergency landing field at Iwo Jima. The crew discussed ditching in the ocean. As they approached Okinawa, they radioed Mayday and received no response. He told the crew to drop flares. Still no response. Without any approvals from air traffic control, the crew maneuvered their aircraft behind two aircraft in line to land. They then lost one of their four engines. As they landed, a second engine went idle. They landed, with only 35 gallons fuel, essentially empty.

The report from the 313th Bomb Wing read as follows:

"Bombed Nagasaki 090158Z (2158 EWT 9:58 PM 8 August 10:589 8/9 Japan) visually with no fighter opposition and no flak. Results 'technically successes' but other factors involved make conference necessary before taking further steps. Visible effects about equal to Hiroshima. Trouble in airplane following delivery requires us to proceed to Okinawa.. Fuel only to get to Okinawa."

We recommend you read the documents on the National Security Archives web site for the full reports.

President Truman did not announce the Nagasaki attack. He did give a radio speech after the attack, but made no mention of it, other than to say this:

"The world will note that the first atomic bomb was dropped on Hiroshima, a military base. That was because we wished in this first attack to avoid, insofar as possible, the killing of civilians. But that attack is only a warning of things to come. If Japan does not surrender, bombs will have to be dropped on her war industries and, unfortunately, thousands of civilian lives will be lost. I urge Japanese civilians to leave industrial cities immediately, and save themselves from destruction."

It's now August 9, 1945, two A-bombs had been dropped successfully on Japan, and, according to intercepts of Japanese message traffic, the Japanese Supreme War Council meeting that day could not agree on how to approach the Americans. In all cases, the Japanese wanted to attach conditions to a surrender, ranging from one (the emperor) to four, the latter three of which included no occupation, no foreign war crimes trials, and acceptance of voluntary Japanese military withdrawals and demobilization.

At this meeting, the fear of domestic upheaval was discussed with some arguing that continuing the war would alleviate domestic anxieties and bring the country together to fight off the Americans.

Throughout, hope continued that the Japanese could achieve a negotiated settlement with the Americans. The prime minister asked the emperor's decision. The emperor said, in round-about language, he would end the war on condition that "the Imperial House, the people and the national territory remain." He said the war was hopeless and there was no chance for victory.

As a result, the Japanese sent a telegram on August 10 via Switzerland and Sweden that they would accept the terms of the Potsdam Declaration upon "the understanding that its does not comprise any demand which prejudices the prerogatives of His Majesty as sovereign ruler." In short, one condition.

On August 10, President Truman, having received the surrender offer, stopped any further employment of the A-bomb. General Marshall informed General Groves that no more A-bombs could be released over Japan without express authority from the President.

It's time to pause again in order to raise the "Soviet Problem" and the "need for speed" mentioned previously.

While the Americans were unsure "how to" end the war, they were sure of one thing: there was a need for speed. It had to end quickly. Operation Downfall's two phases were scheduled for November 1, 1945 and March 1, 1946. As mentioned previously, the political advisors felt the American people would not tolerate a war into 1947.

With Downfall and Blacklist on the table, either way the Americans intended to occupy Japan and assign an American officer to be the Supreme Commander of the Allied Powers during that occupation. But the fly in the ointment was that an American occupation force had to get in there quickly or face the prospect of the Soviets wanting a piece of the occupation and command action. The Soviets might even want to participate in the invasion.


Greater Manchuria is in the various shades of red. While not reflected on this map, please recall that Japan at the time occupied the entire Korean peninsula, Sakhalin Island, and much of the Kurile Island chain as well. Map presented by wikipedia.

The Soviet Union invaded Manchuria on August 6, 1945, the day of the Hiroshima bombing. The Japanese expected the Soviet invasion, but in the fall, not in August 1945. The Soviets moved four armies into Manchuria. This area was considered strategically important to the Soviets, Chinese, and Japanese, and each had long sought ownership of it.


Soviet T–34 medium tanks on the road in Manchuria. Presented by Lone Sentry.

While Japan's force structure in the region was formidable, it had deteriorated in quality over the years and, expecting an American invasion of the Home Islands, Japan moved the veteran divisions back to the homeland. As a result, US leaders worried that the Soviets might advance so rapidly in Manchuria that they would attempt to lay some kind of claim to the Japanese Home Islands and demand to participate in the invasion, occupation and peace process --- muddling the whole works, as they did in Europe.

There had been hope that a Soviet invasion of Manchuria coupled with a Soviet declaration of war against Japan, which came on August might be enough to cause the Japanese to surrender quickly, fearing a Soviet occupation. Such a sudden Japanese surrender would require rapid implementation of Blacklist. In either event, US occupation was needed quickly, which meant a Japanese surrender was needed quickly.

The question of Soviet involvement in the occupation of Japan was raised on August 10 by the Soviets with US Ambassador to Moscow Averill Harriman. Kimie Hara, in the book, Japanese- Soviet Relations Since 1945: Difficult Peace , reported that Stalin raised it again on August 16, 1945, suggesting that the Soviets ought to get all the Kuriles, including Sakhalin, and the northern half of Hokkaido. Hara further said that "Soviet military commanders were 'energetically' undertaking their strategic plan of occupying the 'Northern Territories' of Japan.'"

Even with the emperor's radio announcement, the Soviets continued military actions against Japanese forces on Sakhalin and Shumshu Island in the Kurile Chain.

It is arguable whether the Soviets could have mounted any kind of invasion attempt against northern Japan. Nonetheless, these were uncertain times and it was valid to worry.

Major General Clayton Bissell, shown here, was General Marshall's chief of intelligence. On August 12, he laid out what he saw were the options open to Japan:

  • Drag out what had turned into negotiations by electric wire until they could get something they could live with.
  • Reject all of it and continue hostilities.
  • Accept the Allied proposal to end the war. This proposal on the surface was unconditional surrender with a Supreme Commander of Allied Powers in charge in Japan during an occupation. However, the US felt there was wiggle room in the words to lead the Japanese to understand the emperor's position could remain.

Bissell opined that the first option gave the Japanese the initiative and should not be permitted. He offered that the US would prevail should further hostilities go on, to wit, an invasion. He said A-bombs would not be needed for at least the first 30 days of the invasion, leaving open their use after that, during an invasion. With regard to the last option, Bissell felt the Japanese people would go along with the emperor's decision, however reluctantly, He felt Japanese forces would obey his decision in Manchuria, but they would not surrender to Koreans on the Korean peninsula. A US force wold have to be sent there to accept a Japanese surrender. What might happen in China was a toss up. The Allies would have to act there to maintain control. Elsewhere, Japanese forces would obey the emperor, in Bissell's opinion.

Also on August 12, Japan's Vice Chief of the Army General Staff issued a circular that said, in part:

"As a result of Russia's entrance into the war, the Empire, in the fourth year of its endeavor, is faced with a struggle for the existence of the nation. However, the Imperial Army and Navy are resolutely determined to continue their efforts to preserve the national structure, even if it means the destruction of the Army and Navy ... We will continue the war to the bitter end."

In a telephone conversation of August 13, 1945 between General John E. Hull, shown here, assistant chief of staff for the War Department's Operations Division (OD) and Colonel L. E. Seeman, an associate of General Groves (Manhattan Project), Hull discussed the relationships between employment of further atomic weapons and the impending invasion of the home islands. Recall that two A-bombs had already been dropped. General Hull was active in planning Allied operations throughout the entire war and was seen by many as a top authority on integrating strategy with operations.

Seeman confirmed to Hull that a third bomb was ready, that it could be shipped on August 16, and could be dropped on Japan on August 19. General Curtis Lemay, commander of the 20th AF which had dropped the first two bombs, had already asked Colonel Tibbets if there were any more, and Tibbetts replied to the affirmative, one more, ready to go. Lemay ordered Tibbets to get that third bomb out to Tinian immediately. That process then began.

Hull then started computing with Seeman how many bombs would be available through the end of October. Together they computed that the total bombs that could be available by the end of October, and dropped if required, was seven. Recall that the Operation Downfall - Olympic landings were to commence on Kyushu on November 1, 1945.

Hull, on August 13, was working on a planning assumption that the Japanese would not capitulate despite the two bombs dropped thus far. Several days had already passed without a peep from the Japanese.

Given this planning assumption, Hull then discussed what the targets ought to be, and suggested that they ought to be targets that would support the invasion. In other words, he was pondering using the bombs while the invasion was underway, in Seeman's words, "nearer a tactical use rather than the other (strategic) use."

Seeman responded he had thought about this. He opined that the invasion force would have to be at least six miles away from a target, though he cautioned that he was unsure about whether the Air Force could place it within 500 ft. of the point from which they would compute the six miles.

General MacArthur, like many general officers, was not enamored by the idea of employing the bomb. That said, like Secretary Hull, he did give thought to integrating it as a tactical weapon should the tactical operations at Kyushu and Honshu fail to bring the Japanese to their senses. Admiral Nimitz saw it about the same.

So that was August 13. A military coup in Japan unfolded but failed on August 14. There was also an attempt to steal the recording made by the emperor agreeing to surrender. It failed as well.

On August 14-15, 1945 (we get confused on the impact of the international dateline when we read dates in the research), Japan surrendered unconditionally. President Truman received a message from the Japanese Government on August 14, 1945 which said, among other things:

"His Majesty the Emperor has issued an Imperial rescript regarding Japan's acceptance of the provisions of the Potsdam declaration."

Emperor Hirohito delivered his speech by radio to his people on August 15, 1945 which said, among other things:

"I have ordered the Imperial Government to inform the four Governments of the United States, Great Britain, China and the Soviet Union that our Empire is willing to accept the provisions of their Joint Declaration."

For the sake of his people and royal ambiguity, he called the Potsdam Declaration the "Joint Declaration."


Japanese surrender signatories arrive aboard the USS Missouri in Tokyo Bay to participate in surrender ceremonies, September 2, 1945. A most interesting area of research would be to learn about all the precautionary efforts that US forces had to make to be sure this didn't blow in their faces. Presented by the National Archives.


General Yoshijiro Umezu, Chief of the Army General Staff, signs the Instrument of Surrender on behalf of Japanese Imperial General Headquarters, on board USS Missouri (BB-63), 2 September 1945. Watching from across the table are Lieutenant General Richard K. Sutherland and General of the Army (five star) Douglas MacArthur. Representatives of the Allied powers are behind General MacArthur. Photographed from atop Missouri's 16-inch gun turret # 2. Official U.S. Navy Photograph, now in the collections of the National Archives. Presented by the Naval History Center.

A formal treaty was signed on September 2, 1945, in Tokyo Bay. So that was that. Many of the forces slated to invade now landed unopposed as an occupation force, the occupation began and the rest is history.

The Japanese announcement to accept an unconditional surrender came only 11 weeks and one day before the might of the US military would invade the Home Islands. Our veteran in the grocery store is right to have uttered a sigh of relief. Most of those who would invade were already hardened veterans of the war in the Pacific, and some from the war in Europe.

Many opine that dropping the A-bombs saved many American lives. That is true. How many casualties might result from the Operation Downfall invasion was controversial then and remains so today. The generally accepted figure was that the US would suffer one million casualties. Some even said more.

The truth, thankfully, is no one knows.

D.M. Giangreco prepared a paper on this subject, entitled, "Casualty projections for the US invasion of Japan, 1945-46: Planning and policy implications." He doggedly describes the numerous discussions and papers written on the subject, and then, sums it all up this way:

"Researchers look at the forest of documents created over fifty years ago and almost immediately become lost during their hunt for extreme comments and inconsistencies. The fundamental truth, however, was that the Army and War Department manpower policy of 1945--- in all its aspects--- was established in such a way that the Army could sustain an average of 100,000 casualties per month from November 1945 through the fall of 1946 and still retain relatively fully manned and combat-effective units through its use of new Selective Service inductees and reassigned soldiers from demobilized units. That casualties would be massive was so basic an under standing, that it was functionally a 'self-evident truth' held by decision maker s at virtually all levels. Little or no paper discussion was required or conducted within the Army, and events beyond its purview rendered an invasion unnecessary. The Army, as an institution, believed its soldier s would suffer extreme losses during an invasion of Japan, and all its actions in 1945 were based on that assumption."