WWII - Plans for the invasion of Japan


Bionic SSSO1 plank owner
Aug 14, 2006
I thought you history buffs might find this interesting.

Deep in the recesses of the National Archives in Washington, D.C., hidden
for nearly four decades lie thousands of pages of yellowing and dusty
documents stamped "Top Secret". These documents, now declassified, are the
plans for Operation Downfall, the invasion of Japan during World War II.
Only a few Americans in 1945 were aware of the elaborate plans that had been
prepared for the Allied Invasion of the Japanese home islands. Even fewer
today are aware of the defenses the Japanese had prepared to counter the
invasion had it been launched.

Operation Downfall was finalized during the spring and summer of 1945. It
called for two massive military undertakings to be carried out in succession
and aimed at the heart of the Japanese Empire.
In the first invasion - code named "Operation Olympic"- American combat
troops would land on Japan by amphibious assault during the early morning
hours of November 1, 1945 - 61 years ago. Fourteen combat divisions of
soldiers and Marines would land on heavily fortified and defended Kyushu,
the southernmost of the Japanese home islands, after an unprecedented naval
and aerial bombardment.

The second invasion on March 1, 1946 - code named "Operation Coronet"-
would send at least 22 divisions against 1 million Japanese defenders on the
main island of Honshu and the Tokyo Plain. It's goal: the unconditional
surrender of Japan. With the exception of a part of the British Pacific
Fleet, Operation Downfall was to be a strictly American operation. It called
for using the entire Marine Corps, the entire Pacific Navy, elements of the
7th Army Air Force, the 8 Air Force (recently redeployed from Europe), 10th
Air Force and the American Far Eastern Air Force. More than 1.5 million
combat soldiers, with 3 million more in support or more than 40% of all
servicemen still in uniform in 1945 - would be directly involved in the two
amphibious assaults. Casualties were expected to be extremely heavy.

Admiral William Leahy estimated that there would be more than 250,000
Americans killed or wounded on Kyushu alone. General Charles Willoughby,
chief of intelligence for General Douglas MacArthur, the Supreme Commander
of the Southwest Pacific, estimated American casualties would be one million
men by the fall of 1946. Willoughby's own intelligence staff considered this
to be a conservative estimate.

During the summer of 1945, America had little time to prepare for such an
endeavor, but top military leaders were in almost unanimous agreement that
an invasion was necessary. While naval blockade and strategic bombing of
Japan was considered to be useful, General MacArthur, for instance, did not
believe a blockade would bring about an unconditional surrender. The
advocates for invasion agreed that while a naval blockade chokes, it does
not kill; and though strategic bombing might destroy cities, it leaves whole
armies intact.

So on May 25, 1945, the Joint Chiefs of Staff, after extensive
deliberation, issued to General MacArthur, Admiral Chester Nimitz, and Army
Air Force General Henry Arnold, the top secret directive to proceed with the
invasion of Kyushu. The target date was after the typhoon season.

President Truman approved the plans for the invasions July 24. Two days
later, the United Nations issued the Potsdam Proclamation, which called upon
Japan to surrender unconditionally or face total destruction. Three days
later, the Japanese governmental news agency broadcast to the world that
Japan would ignore the proclamation and would refuse to surrender. During
this same period it was learned -- via monitoring Japanese radio broadcasts
-- that Japan had closed all schools and mobilized its school children, was
arming its civilian population and was fortifying caves and building
underground defenses.

Operation Olympic called for a four pronged assault on Kyushu. Its purpose
was to seize and control the southern one-third of that island and establish
naval and air bases, to tighten the naval blockade of the home islands, to
destroy units of the main Japanese army and to support the later invasion of
the Tokyo Plain. The preliminary invasion would began October 27 when the
40th Infantry Division would land on a series of small islands west and
southwest of Kyushu. At the same time, the 158th Regimental Combat Team
would invade and occupy a small island 28 miles south of Kyushu. On these
islands, seaplane bases would be established and radar would be set up to
provide advance air warning for the invasion fleet, to serve as fighter
direction centers for the carrier-based aircraft and to provide an emergency
anchorage for the invasion fleet, should things not go well on the day of
the invasion.

As the invasion grew imminent, the massive firepower of the Navy - the
Third and Fifth Fleets -- would approach Japan. The Third Fleet, under
Admiral William "Bull" Halsey, with its big guns and naval aircraft, would
provide strategic support for the operation against Honshu and Hokkaido.
Halsey's fleet would be composed of battleships, heavy cruisers, destroyers,
dozens of support ships and three fast carrier task groups. From these
carriers, hundreds of Navy fighters, dive bombers and torpedo planes would
hit targets all over the island of Honshu. The 3,000 ship Fifth Fleet, under
Admiral Raymond Spruance , would carry the invasion troops

Several days before the invasion, the battleships, heavy cruisers and
destroyers would pour thousands of tons of high explosives into the target
areas. They would not cease the bombardment until after the land forces had
been launched. During the early morning hours of November 1, the invasion
would begin. Thousands of soldiers and Marines would pour ashore on beaches
all along the eastern, southeastern, southern and western coasts of Kyushu.
Waves of Helldivers, Dauntless dive bombers, Avengers, Corsairs, and
Hellcats from 66 aircraft carriers would bomb, rocket and strafe enemy
defenses, gun emplacements and troop concentrations along the beaches.

The Eastern Assault Force consisting of the 25th, 33rd, and 41st Infantry
Divisions, would land near Miyaski, at beaches called Austin, Buick,
Cadillac, Chevrolet, Chrysler, and Ford, and move inland to attempt to
capture the city and its nearby airfield. The Southern Assault Force,
consisting of the 1st Cavalry Division, the 43rd Division and Americal
Division would land inside Ariake Bay at beaches labeled DeSoto, Dusenberg,
Essex, Ford, and Franklin and attempt to cap ture Shibushi and the city of
Kanoya and its airfield.

On the western shore of Kyushu, at beaches Pontiac, Reo, Rolls Royce,
Saxon, Star, Studebaker, Stutz, Winston and Zephyr, the V Amphibious Corps
would land the 2nd, 3rd, and 5th Marine Divisions, sending half of its force
inland to Sendai and the other half to the port city of Kagoshima.

On November 4, the Reserve Force, consisting of the 81st and 98th Infantry
Divisions and the 11th Airborne Division, after feigning an attack on the
island of Shikoku, would be landed -- if not needed elsewhere -- near
Kaimondake, near the southernmost tip of Kagoshima Bay, at the beaches
designated Locomobile, Lincoln, LaSalle, Hupmobile, Moon, Mercedes, Maxwell,
Overland, Oldsmobile, Packard, and Plymouth

Olympic was not just a plan for invasion, but for conquest and occupation as
well. It was expected to take four months to achieve its objective, with the
three fresh American divisions per month to be landed in support of that
operation if needed. If all went well with Olympic, Coronet would be
launched March 1,1946. Coronet would be twice the size of Olympic, with as
many as 28 divisions landing on Honshu

All along the coast east of Tokyo, the American 1st Army would land the 5th,
7th, 27th, 44th, 86th, and 96th Infantry Divisions, along with the 4th and
6th Marine Divisions. At Sagami Bay, just south of Tokyo, the entire 8th and
10th Armies would strike north and east to clear the long western shore of
Tokyo Bay and attempt to go as far as Yokohama. The assault troops landing
south of Tokyo would be the 4th, 6th, 8th, 24th, 31st, 37th, 38th, and 8th
Infantry Divisions, along with the 13th and 20th A rmored Divisions
following the initial assault, eight more divisions - the 2nd, 28th, 35th,
91st, 95th, 97th, and 104th Infantry Divisions and the 11th Airborne
Division -- would be landed. If additional troops were needed, as expected,
other divisions redeployed from Europe and undergoing training in the United
States would be shipped to Japan in what was hoped to be the final push.

Captured Japanese documents and post war interrogations of Japanese
military leaders disclose that information concerning the number of Japanese
planes available for the defense of the home islands was dangerously in
error. During the sea battle at Okinawa alone, Japanese Kamikaze aircraft
sank 32 Allied ships and damaged more than 400 others. But during the summer
of 1945, American top brass concluded that the Japanese had spent their air
force since American bombers and fighters daily flew unmolested over Japan.

What the military leaders did not know was that by the end of July the
Japanese had been saving all aircraft, fuel, and pilots in reserve, and had
been feverishly building new planes for the decisive battle for their
homeland. As part of Ketsu-Go, the name for the plan to defend Japan -- the
Japanese were building 20 suicide takeoff strips in southern Kyushu with
underground hangars. They also had 35 camouflaged airfields and nine
seaplane bases.

On the night before the expected invasion, 50 Japanese seaplane bombers,
100 former carrier aircraft and 50 land based army planes were to be
launched in a suicide attack on the fleet. The Japanese had 58 more
airfields in Korea, western Honshu and Shikoku, which also were to be used
for massive suicide attacks.

Allied intelligence had established that the Japanese had no more than
2,500 aircraft of which they guessed 300 would be deployed in suicide
attacks. In August 1945, however, unknown to Allied intelligence, the
Japanese still had 5,651 army and 7,074 navy aircraft, for a total of 12,725
planes of all types. Every village had some type of aircraft manufacturing
activity. Hidden in mines, railway tunnels, under viaducts and in basements
of department stores, work was being done to construct new planes.

Additionally, the Japanese were building newer and more effective models of
the Okka, a rocket-propelled bomb much like the German V-1, but flown by a
suicide pilot. When the invasion became imminent, Ketsu-Go called for a
fourfold aerial plan of attack to destroy up to 800 Allied ships. While
Allied ships were approaching Japan, but still in the open seas, an initial
force of 2,000 army and navy fighters were to fight to the death to control
the skies over Kyushu. A second force of 330 navy combat pilots were to
attack the main body of the task force to keep it from using its fire
support and air cover to protect the troop carrying transports. While these
two forces were engaged, a third force of 825 suicide planes was to hit the
American transports.

As the invasion convoys approached their anchorages, another 2,000 suicide
planes were to be launched in waves of 200 to 300 , to be used in hour by
hour attacks. By mid-morning of the first day of the invasion, most of the
American land-based aircraft would be forced to return to their bases,
leaving the defense against the suicide planes to the carrier pilots and the
shipboard gunners.

Carrier pilots crippled by fatigue would have to land time and time again
to rearm and refuel. Guns would malfunction from the heat of continuous
firing and ammunition would become scarce. Gun crews would be exhausted by
nightfall, but still the waves of kamikaze would continue. With the fleet
hovering off the beaches, all remaining Japanese aircraft would be committed
to nonstop suicide attacks, which the Japanese hoped could be sustained for
10 days. The Japanese planned to coordinate their air strikes with attacks
from the 40 remaining submarines from the Imperial Navy -- some armed with
Long Lance torpedoes with a range of 20 miles -- when the invasion fleet was
180 miles off Kyushu.

The Imperial Navy had 23 destroyers and two cruisers which were
operational. These ships were to be used to counterattack the American
invasion. A number of the destroyers were to be beached at the last minute
to be used as anti-invasion gun platforms. Once offshore, the invasion fleet
would be forced to defend not only against the attacks from the air, but
would also be confronted with suicide attacks from sea. Japan had
established a suicide naval attack unit of midget submarines, human
torpedoes and exploding motorboats.

The goal of the Japanese was to shatter the invasion before the landing.
The Japanese were convinced the Americans would back off or become so
demoralized that they would then accept a less-than-unconditional surrender
and a more honorable and face-saving end for the Japanese. But as horrible
as the battle of Japan would be off the beaches, it would be on Japanese
soil that the American forces would face the most rugged and fanatical
defense encountered during the war.

Throughout the island-hopping Pacific campaign, Allied troops had always
out numbered the Japanese by 2 to 1 and sometimes 3 to 1. In Japan it would
be different. By virtue of a combination of cunning, guesswork, and
brilliant military reasoning, a number of Japan's top military leaders were
able to deduce, not only when, but where, the United States would land its
first invasion forces.
Facing the 14 American divisions landing at Kyushu would be 14 Japanese
divisions, 7 independent mixed brigades, 3 tank brigades and thousands of
naval troops. On Kyushu the odds would be 3 to 2 in favor of the Japanese,
with 790,000 enemy defenders against 550,000 Americans. This time the bulk
of the Japanese defenders would not be the poorly trained and ill-equipped
labor battalions that the
Americans had faced in the earlier campaigns.

The Japanese defenders would be the hard core of the home army. These
troops were well-fed and well equipped. They were familiar with the terrain,
had stockpiles of arms and ammunition, and had developed an effective system
of transportation and supply almost invisible from the air. Many of these
Japanese troops were the elite of the army, and they were swollen with a
fanatical fighting spirit. Japan's network of beach defenses consisted of
offshore mines, thousands of suicide scuba divers attacking landing craft,
and mines planted on the beaches. Coming ashore, the American Eastern
amphibious assault forces at Miyazaki would face three Japanese divisions,
and two others poised for counter attack. Awaiting the Southeastern attack
force at Ariake Bay was an entire division and at least one mixed infantry

On the western shores of Kyushu, the Marines would face the most brutal
opposition. Along the invasion beaches would be the three Japanese
divisions, a tank brigade, a mixed infantry brigade and an artillery
command. Components of two divisions would also be poised to launch
counterattacks. If not needed to reinforce the primary landing beaches, the
American Reserve Force would be landed at the base of Kagoshima Bay November
4, where they would be confronted by two mixed infantry brigades, parts of
two infantry divisions and thousands of naval troops.

All along the invasion beaches, American troops would face coastal
batteries, anti-landing obstacles and a network of heavily fortified
pillboxes, bunkers, and underground fortresses. As Americans waded ashore,
they would face intense artillery and mortar fire as they worked their way
through concrete rubble and barbed-wire entanglements arranged to funnel
them into the muzzles of these Japanese guns.
On the beaches and beyond would be hundreds of Japanese machine gun
positions, beach mines, booby traps, trip-wire mines and sniper units.
Suicide units concealed in "spider holes" would engage the troops as they
passed nearby. In the heat of battle, Japanese infiltration units would be
sent to reap havoc in the American lines by cutting phone and communication
lines. Some of the Japanese troops would be in American uniform,
English-speaking Japanese officers were assigned to break in on American
radio traffic to call off artillery fire, to order retreats and to further
confuse troops.

Other infiltration with demolition charges strapped on their chests or
backs would attempt to blow up American tanks, artillery pieces and
ammunition stores as they were unloaded ashore.

Beyond the beaches were large artillery pieces situated to bring down a
curtain of fire on the beach. Some of these large guns were mounted on
railroad tracks running in and out of caves protected by concrete and steel.
The battle for Japan would be won by what Simon Bolivar Buckner, a
lieutenant general i n the Confederate army during the Civil War, had called
"Prairie Dog Warfare." This type of fighting was almost unknown to the
ground troops in Europe and the Mediterranean. It was peculiar only to the
soldiers and Marines who fought the Japanese on islands all over the Pacific
-- at Tarawa, Saipan, Iwo Jima and Okinawa.

Prairie Dog Warfare was a battle for yards, feet and sometimes inches. It
was brutal, deadly and dangerous form of combat aimed at an underground,
heavily fortified, non-retreating enemy. In the mountains behind the
Japanese beaches were underground networks of caves, bunkers, command posts
and hospitals connected by miles of tunnels with dozens of entrances and
exits. Some of these complexes could hold up to 1,000 troops. In addition to
the use of poison gas and bacteriological warfare (which the Japanese had
experimented with), Japan mobilized its citizenry.

Had Olympic come about, the Japanese civilian population, inflamed by a
national slogan - "One Hundred Million Will Die for the Emperor and Nation"
- were prepared to fight to the death. Twenty Eight Million Japanese had
become a part of the National Volunteer Combat Force. They were armed with
ancient rifles, lunge mines, satchel charges, Molotov cocktails and one-shot
black powder mortars. Others were armed with swords, long bows, axes and
bamboo spears. The civilian units were to be used in nighttime attacks, hit
and run maneuvers, delaying actions and massive suicide charges at the
weaker American positions. At the early stage of the invasion, 1,000
Japanese and American soldiers would be dying every hour.

The invasion of Japan never became a reality because on August 6, 1945, an
atomic bomb was exploded over Hiroshima. Three days later, a second bomb was
dropped on Nagasaki.
Within days the war with Japan was at a close. Had these bombs not been
dropped and had the invasion been launched as scheduled, combat casualties
in Japan would have been at a minimum of the tens of thousands. Every foot
of Japanese soil would have been paid for by Japanese and American lives.

One can only guess at how many civilians would have committed suicide in
their homes or in futile mass military attacks. In retrospect, the 1 million
American men who were to be the casualties of the invasion, were instead
lucky enough to survive the war. Intelligence studies and military estimates
made 50 years ago, and not latter-day speculation, clearly indicate that the
battle for Japan might well have resulted in the biggest blood-bath in the
history of modern warfare.

Far worse would be what might have happened to Japan as a nation and as a
culture. When the invasion came, it would have come after several months of
fire bombing all of the remaining Japanese cities. The cost in human life
that resulted from the two atomic blasts would be small in comparison to the
total number of Japanese lives that would have been lost by this aerial

With American forces locked in combat in the south of Japan, little could
have prevented the Soviet Union from marching into the northern half of the
Japanese home islands. Japan today could be divided much like Korea and
Germany. The world was spared the cost of Operation Downfall, however,
because Japan formally surrendered to the United Nations September 2, 1945,
and World War II was over. The aircraft carriers, cruisers and transport
ships scheduled to carry the invasion troops to Japan, ferried home American
troops in a gigantic operation called Magic Carpet.

In the fall of 1945, in the aftermath of the war, few people concerned
themselves with the invasion plans. Following the surrender, the classified
documents, maps, diagrams and appendices for Operation Downfall were packed
away in boxes and eventually stored at the National Archives. These plans
that called for the invasion of Japan paint a vivid description of what
might have been one of the most horrible campaigns in the history of man.
The fact that the story of the invasion of Japan is locked up in the
National Archives, and is not told in our history books is something for
which all Americans can be thankful.