After Hitler took the coward’s way out on April 30th 1945, the Second World War continued for
over three months. German resistance collapsed fairly quickly, but in the east, Imperial Japan
was digging in for the long haul. This is the story of the planned defence of the Japanese
Home Islands, which would have been the largest and most costly operation of the entire war.
The Allies had spent five and a half years gradually pushing the Japanese
back toward the Home Islands. Every campaign, every island-hop, and every step had cost them
tremendous amounts of sweat and blood. The Battle of Okinawa demonstrated that the Japanese were
still utterly committed, and would make the Allies pay for every metre of ground with a litre of
blood. No one, save for a few scientists and the President, knew about America’s atomic weapons.
When they pictured the coming invasion, all they could see was an endless battle of attrition.
Japan’s mountainous geography meant there were only two viable landing beaches in the
entire country, one on the southern island of Kyushu and the other on the Kanto Plain
next to Tokyo. The Japanese knew this just as well as the Allies, giving them a key strategic
advantage. They may not have known when, but they certainly knew where the Allies were coming.
The Allied invasion plan was codenamed “Downfall” and was split into two phases:
Operation Olympic in Kyushu and Operation Coronet on the Kanto Plain. Since the
Japanese were sure to throw everything they had into the defence of these two zones,
the Allies were forced to resort to the crudest method of waging war: sheer numbers.
As part of Operation Olympic, the Allies would have to assemble the
largest armada the world had ever seen. Twenty-four battleships,
42 aircraft carriers, and 400 destroyers would escort 14 infantry divisions to the beachhead.
In the skies, this gargantuan force was supported by no less than 1,000 B-29s of the 20th Air Force.
The invasion would have been the largest military operation ever seen, and that was just phase one!
The Allies, and especially the Americans,
had raised the stakes far higher than Japan could afford.
Where any other country would have folded and acquiesced to surrender, the Japanese went all in.
Their plan was as simple as it was horrific: cause such devastation to both themselves and
the invaders that the Allies would be forced to accept Japanese conditions of surrender.
They hoped that when the bodies of a million servicemen came home to the United States,
the war-weary populace would demand the President let the Japanese Imperial family off the hook,
even though US propagandists had branded them war criminals.
What were the Japanese admirals and generals willing to sacrifice to see this goal achieved?
Everything, starting with the entire civilian population. So-called Volunteer Fighting Corps
were established across the country by government officers. All males aged between 15 and 60 and all
females aged 17 to 50 were conscripted into these militia units. Twenty-eight million
civilians were considered “Combat capable,” but only 2 million were properly organised.
None had uniforms or equipment, and they were armed with whatever they could find.
The lucky ones were given swords, bows, long knives, or Molotov cocktails.
The unlucky ones made do with sticks and other bits of wood. Yukiko Kasai, a high
school girl mobilised as part of this so-called volunteer force, was given a dressmaker’s awl and
told “Even killing one American soldier will do. You must aim for the abdomen.”
Japanese high command planned for these stick-wielding units of high school girls
and frail old men to act as a second line of defence behind the soldiers and sailors.
They were supposed to throw their lives away as part of a campaign
for "The Glorious Death of One Hundred Million.”
Remember, this was all to prevent Hirohito and his mates from being tried for war crimes.
And these civilians would likely have seen action, as the first line of defence was,
essentially, a gigantic kamikaze mission.
When it became clear Japan was losing the war, the Army and Navy began pulling their
aircraft back to the Home Islands. Every single plane, including trainers and air transports,
was fitted out for kamikaze attack. By the end of June 1945, 10,000 kamikaze planes were ready.
They were loaded with the minimum amount of fuel required for the pilots to get them to the landing
beaches. From there, the pilots were trained to recognise landing craft as their primary targets.
By this point in the war, most of Japan’s experienced pilots had been killed, so it was
left to the young and inexperienced to lead the kamikaze attack. Generals, safe in their bunkers,
planned to order teenage boys to sacrifice themselves in the hope that they might sink
enough transports to make the Allies temporarily call off the attack. But it didn’t stop there.
Beneath the waves, legions of suicidal frogmen waited to strike. Called “Fukuryu” by the Japanese
Navy, these frogmen were equipped with a diving suit and a small mine on the end of a bamboo pole.
They would deploy from submerged bunkers and walk toward the landing craft underwater.
They were fed through tubes that provided liquified food and carried enough air for
several hours of operation. When the craft passed overhead, they were to thrust their pole upwards,
detonating the mine and putting the boat out of action. The explosion would also kill the diver.
The Navy planned to deploy 6,000 Fukuryu, but by mid-August only 1,000 diving suits were available.
Alongside the Fukuryu, the Navy also deployed 120 Kaiten manned torpedoes and 2,412 kamikaze
motorboats. The crew of these boats were also ordered to target the landing craft,
rather than the destroyer escorts, to cause maximum casualties.
Crew for the manned torpedos and kamikaze motorboats were supposed to be volunteers,
but this was rarely the case. Like their brothers in the skies,
most were volunteered by their commanders or shamed into volunteering by political officers.
Behind the screen of Kamikaze aircraft, Fukuryu divers, and suicide boats, Japanese soldiers and
sailors stood ready to defend the beaches. They were armed with a vast assortment of weapons which
included captured Lee-Enfield rifles from the fall of Singapore and German Karabiner 98s taken
from the Chinese. When no weapons were available, conscripts were issued with a “National Simplified
Rifle.” This was nothing more than a block of wood with a notch carved into the top, where a
bolt action and smoothbore barrel were clumsily tied down. This weapon usually had no sights
and was single-shot. Its designs were produced by the Japanese war office and distributed to
small-scale workshops around the country, meaning no two National Simplified Rifles were the same.
Some were chambered with pistol cartridges while others used rifle ammunition.
Some didn’t even use bullets, relying on a matchlock or percussion-cap mechanism and
a black powder charge. These were the weapons Japanese soldiers and sailors
would wield against American semi-automatic M1 Garands, M1 Carbines, and Thompson SMGs.
It was never formalised, but even Emperor Hirohito himself admitted that the battles on the
landing beaches would define the entire Allied invasion. All of the Army and Navy’s strength,
as well as virtually all of its ammunition, was concentrated at Kyushu and Kanto Plain.
There could be no second wave of kamikaze attacks, and with the civilians armed and
ready behind the soldiers and sailors, there was no one to work in the factories to produce
more weapons or ammunition. The battle on the beach would have been all-or-nothing.
Casualty predictions varied considerably,
with some studies expecting losses of up to four million Americans,
and upwards of ten million Japanese civilian casualties. Thankfully, it was not to be.
On August 15th, a week after the atomic bombings of Hiroshima and Nagasaki,
Emperor Hirohito stepped in. On the advice of the Prime Minister and going against
the interests of the Army and Navy, Hirohito unconditionally surrendered Japan to the Allies.
In his surrender speech, he described atomic weapons as
“most cruel” and highlighted they could “take the toll of many innocent lives.”
All this from a man who was prepared to send schoolgirls to the front lines armed with sewing
needles, and who would sell the lives of one hundred million people to save his own skin.
THAT was the insane story of the planned defence of the Japanese Home Islands and
the lengths Japan’s leaders would go to save themselves from justice.
But what do YOU think? Did YOU know the Japanese Navy had thousands of suicidal frogmen? Do YOU
think the Allies could have starved the Japanese out? Do YOU think Emperor Hirohito was a war
criminal, or should the blame go to the admirals and generals? Let us know in the comments!