Operation Downfall, The Planned Invasion of Japan on November 1st. 1945
This is a work in progess, here are some pictures.
When this operation was planned, very few of the American people were aware of the detailed operation for the Allied invasion of Japan, and even today, I do not believe there is widespread appreciation of these plans, or of the defences that the Japanese had prepared to combat such an invasion.
At that time, I was Lieutenant RAN, serving in the 8 inch gunned cruiser HMAS Shropshire, which had been given to the Royal Australian Navy, organised by Winston Churchill, to be gifted by the British Admiralty, to replace HMAS Canberra, sunk by the Imperial Japanese Navy with the US heavy cruisers Quincy, Astoria, and Vincennes, at the Battle of Savo Island on the 9th. of August 1942. On that occasion, fate found me as the Officer of the Watch on Canberra's bridge when this battle commenced. Many of the survivors of the Canberra had also joined Shropshire's crew.
For several years, Shropshire had been part of a United States Navy, Bombardment Group Task Force, and had seen action at Leyte, The Battle of Surigao Straits, and the Lingayen Gulf and Borneo landings.
When the two atomic bombs were unleashed on Japan, Shropshire was at Subic Bay in the Philippines, and prior to that time, the general rumour around our ship had been, that we would soon be part of an invasion force pitted against the Japanese homeland.
On a personal note, I was delighted with President Harry Truman's decision to use the atom bomb, and bring the Pacific War to a conclusion. I, like my shipmates had had enough, Shropshire had been a most efficient and lucky ship, we had not lost one man to enemy action, but, how much longer would this fact obtain? Now, at long last, my six years of war at sea, or overseas, were over. I had survived.
Shropshire now sailed for Tokyo Bay, to be present when the Japanese nation finally beaten, formally surrendered, on board the USS Missouri, on the morning of September 2nd. 1945.
Background to Invasion Plans.
But, it was generally agreed that neither a Naval blockade, or strategic bombing of Japanese cities was likely to force an unconditional surrender of the Japanese nation.
The United States Joint Chiefs of Staff, on the 25th. of May 1945, issued to Admiral Chester Nimitz, Army Air Force General Hap Arnold, and General Douglas MacArthur, a top secret directive to proceed with the invasion of the Island of Kyushu.
On the 25th. of July that year, President Harry Truman approved these invasion plans, and only two days later, the United Nations issued the Potsdam Proclamation, this called upon Japan to unconditionally surrender, the only alternative, total destruction.
It took but three more days before the Japanese Government News Agency told the world it would ignore that Proclamation, and it would not surrender.
The die was cast, it appeared that a fight to the death was on!!
Plans for the invasion of the Japanese Homeland.
Forces to take part.
The entire Marine Corps, and all the Pacific Fleet, the 7th. Army Airforce, the 8th. Air Force, the 10th. Air Force, and the American Far East Air Force would be deployed. More than 1.5 million combat soldiers with another 3 million in support, all of which totalled 40% of all United States service people in uniform in 1945 would be involved.
Casualities were expected to be high, as the Japanese strongly repulsed any attack and threat to their homeland.
Following the established pattern of invading Japanese occupied territory in the Pacific, for several days prior to Invasion Day, Admiral Bull Halsey’s battleships, heavy cruisers, supported by the Fleet destroyers would pour a solid curtain of high explosives onto the target areas. I would have expected Shropshire to have been a part of this bombardment force.
Dauntless Dive bombers, Avengers, Corsairs and Hellcats from sixty six Aircraft Carriers would pour bombs, strafe enemy positions and troop concentrations on and around the beach heads.
By the time Admiral Raymond Spruance’s 3,000 ship fleet, carrying the invasion forces arrived on the 1st. day of November 1945, it was believed the landing beach defences would have been pulverised, and be relatively cleared of the enemy.
Eastern Assault Force.
Airfields were of paramount importance, a lesson harshly learned in the Pacific campaign, without air cover, both the invading forces on land, and their naval support ships were dangerously vulnerable to enemy air and suicide sttacks.
It is quite obvious that the planners for this invasion, all enjoyed their motor cars, by naming all the proposed landing beaches after these famous vehicle names.
Objective of Olympic.
It was felt that four months were probably needed for its objective to be reached, and three divisions a month would, if needed, also be landed to back up the original forces.
It was to be twice the size of Olympic, with up to twenty eight Divisions planned to land on Honshu. Along the coast east of Tokyo, the US 1st. Army would land the 5th, 7th, 27th, 44th, 86th, and 96th Infantry Divisions, plus two Marine Divisions, the 4th and 6th.
Just south of Tokyo at Sagami Bay, the total 8th and 10th Armies would move north and east to grab Yokohama. Troops landing south of Tokyo, would be the 4th, 6th, 8th, 24th, 31st, 32nd, 37th, 38th, and 87th Infantry Divisions, backed up by two Armoured Divisions, the 13th, and 20th.
After the initial assault, these troops would be augmented by another eight divisions, namely the 2nd, 28th, 35th, 91st, 95th, 97th, and 104th Infantry, with the 11th Airborne Division backing them up.
The endless stream of food, gasoline, ammunition, medical needs, equipment, reserves of manpower etc that had to flow across the Pacific from both the United States and Australia would be an organisational nightmare.
Numbers of Japanese Aircraft available to defend their Homeland.
But, the Japanese were deliberately husbanding their aircraft, fuel and pilots, holding them in reserve against the day that their country would be invaded by US forces. Allied intelligence considered 2,500 Japanese aircraft were available, with perhaps an additional 300 available to be deployed in suicide attacks.
In fact, how very wrong these estimates were, in August of 1945, the Japanese nation had 5, 651 Army and 7,074 Navy aircraft, ie 12,725 aircraft of all types available to defend the Homeland.
In addition, a newer and more effective model of Okka, a rocket propelled bomb, like the German V-1, but flown by a sucide pilot, were being built and becoming available.
Japanese plans to fight off the invading forces.
A second group of 330 Navy combat pilots would attack the Task Force, aiming to prevent its fire support, and provision of air cover for the troop transports.
In addition, a third group made up of 825 suicide aircraft would hit the incoming troopships.
As the convoys of invasion ships closed on their proposed anchorages, another 2,000 suicide aircraft would be launched, 300 at a time, hour after hour.
During the invasion of Lingayen Gulf in January 1945, I had seen many kamikaze attacks on the bombardment group of ships, and also on the invasion fleet. I saw a large number of hits on ships with devastating results, eg, our sister ship HMAS Australia, only 600 yards away from Shropshire, was hit five times by kamikaze aircraft, resulting in a large loss of life.
It was my experience, that no matter how many of our aircraft flew the Combat Air Patrol, and no matter how intense the anti-aircraft fire from the fleet, a number of the determined enemy kamikaze pilots always got through, to then crash on the ship they had individually selected as a target.
To be subjected to such attacks, day after day, over a long period, becomes mind numbing, one can sense the slow lowering of morale in a crew, you start to think, we as a ship, and her company, and I, as an individual, cannot continue to be lucky, we escaped yesterday, we escaped again today, but: How much longer can we continue? Will our time to become a victim come tomorrow?
I can only reiterate, when President Truman made his decision to drop those two atomic bombs, and the Japanese accepted unconditional surrender, I was a happy and delighted young man of 23 years of age , I was going to live, I had survived WW2, I had been involved since September 1939 across all the oceans of the world since I was 17.
However, what submarines might have been available, would be used to attack the
Downfall P 7
What ever the number of Japanese submarines still in existence might have been, they would be used to attack the invasion force, backed up by midget submarines, Kaiten, ridden and guided by a sucide pilot to become human torpedoes, plus motor boats packed with explosives.
The carnage inflicted by these methods of attack, can only be contemplated with trepidation.
The Japanese hoped to be able to shatter the Allies morale, and force the invasion fleet to back off, and hopefully, from the Japanese viewpoint, accept a more honourable and face saving prospect than unconditional surrender.
In most of the Pacific fighting during the island hopping campaign, our forces always outnumbered the Japanese forces by at least 2to1, and at times at 3 to 1.
The wags in my ship used to describe a US invasion force, they landed their supplies on the beach, built it up, and up, and still up, until it became so large that it then toppled over and crushed all the enemy. It was now time for the Marines/Troops to storm ashore to victory.
Although an exaggeration, there is still an element of truth to this whimsy!
The land forces were backed up by offshore mines, thousands of suicide scuba divers to attack the incoming laden landing craft, and then mine infested beaches.
Backing up the invasion beach defences would be coastal batteries, anti-landing obstacles, heavily fortified pill boxes, bunkers, and underground fortresses.
On the actual beaches would be a myriad of beach mines, Japanese machine gun nests, booby traps, trip wires to set off explosive devices, and sucide units ready to rush out of their spider type holes to cut down the invading army.
Suicide bombers with explosive charges strapped to their bodies ( just as the Arabs in Israel are using such devices today in their battle against the Jews ) would throw themselves onto tanks, and artillery pieces as they came ashore.
This may sound more like a Hollywood set in a far fetched war movie, but it was very much the fate that awaited the US invasion forces on that morning of the 1st of
Large guns beyond the beach head would lay down a withering fire on the landing areas. The fighting would be totally alien to that encountered by the troops who had fought the Germans in Europe, here in the Pacific, it was often fanatical, as witnessed at places such as Tarawa, Iwo Jima, Okinawa, foot by foot, yard by yard, a fight to the death.
At an early stage of this invasion up to 1,000 Japanese could be expected to die every hour.
Very thankfully, none of the above came to pass, on the 6th. of August 1945, an atomic bomb was detonated over Hiroshima, and three days later, a second atom bomb was used at Nagasaki.
It was enough, in a few more days the Japanese nation surrendered unconditionally, by the use of those two atomic devices, up to a million US casualities were spared.
As I have already indicated in my introduction, I was most grateful in being spared from being a part of that bombardment of the Japanese mainland, and to know, at last it was all over, I would, I had survived 6 years of war at sea, in most theatres where it had been fought from the 3rd. of September 1939 to September the 2nd. 1945.
My teen years gone, to have grown up very quickly in the blast furnace of the Battle of the Atlantic, the Battle of Savo Island, the Pacific campaigns, landings in the Philippines and Borneo, and now to be present in Tokyo Bay on the 2nd. of September for the Japanese surrender.
I had much to be grateful for in my final release from the shackles of WW2, from a teenager of 17, I was now a man of 23.
( a ) Naval Air Station on Tokyo Bay.
entering and leaving harbour.
Each Division had an executive Lieutenant in charge, and a senior seaman Petty Officer as Captain of Top.
A few days prior to the surrender being signed, the Commander sent for me and said, “ Now that peace is almost upon us, we will need to scrub both the upper deck and quarterdeck, and maintain them, in a pristine condition as we did in peace time. ( during the war, the decks were painted blue/grey so that that were less visible to any enemy aircraft. )
Take the ship’s landing craft and the four Captains’ of Top, go ashore and look for a load of sand to scour the decks.”
I duly scanned the chart of the Tokyo Bay area, and found a Naval Air Station marked thereon, that looked a likely spot to explore.
Off we went, on arrival, the tarmac was crammed with literally hundreds of aircraft, gassed up, ready to take off and attack the Allied invasion.
On the Emperor’s command to surrender, this large Naval Air Station had been evacuated, it was quiet and empty, not a single Japanese Naval Officer or sailor in sight, the base abandoned, bereft, everyone had simply walked away.
It had obviously been an area for gathering shipping intelligence, aircraft cameras, aircraft sextants, large dark rooms crammed with photographic and enlarging equipment, work shops full of maintenance equipment, optical workshops fitted with jeweller’s lathes, an absolute cornucopia of goodies, but not a single grain of sand.
A raft of items just waiting to be liberated, and we obliged.
( b ) Exploratory Expeditions ashore.
Our Navigating Officer used a Barr and Stroud, Metre based range finder, to work out the distance from our anchorage whenever we were coming into a specific area to anchor. It had a spigot that fitted into a hole on the wing of the bridge, on our entrance to Tokyo Bay he was using this instrument, and the Captain suddenly called out Pilot! The Navigator swung round to respond, knocked the range finder, which went flying from its housing to splash into the sea, some 60 feet below, and
quickly sink into the depths of Tokyo Bay.
During a visit to Naval caves, the Japanese were inveterate cave diggers, I had found an area crammed with Naval equipment of British origin, and I believe it had been captured from Singapore when the Japanese had overrun that city, and transshipped here to Japan.
I came across boxes of brand new Barr and Stroud one metre based range finders, and quickly collected half a dozen to take back for our Navigator. He was personally liable to pay for the one he had lost, now, the serial numbers were going to be different, but that was unlikely to pose a problem for him.
( c ) A Landing Craft Personnel, and a Jeep.
( d ) Atsugi Airfield.
They record, with a startling vividness, what, no doubt would have proven to be the most dreadful campaign in the annals of human conflict.
Even today, at this distance from the end of WW2 in the Pacific, very little has been disseminated about Operation Downfall.
An interesting article from Dennis Giangreco at the US Army Command and General Staff College about Casualties expected from Operation Downfall.
December 2004 Newsletter of the Society for Historians of American Foreign Relations