Massachusetts file photo

Preparations for Invasion of Japan

14 Jul 1945 - 9 Aug 1945

Contributor: C. Peter Chen

The eventual successful development of the atomic weapons would play a role in the Japanese decision to surrender, but few had the knowledge of the existence of such a research program. Those who knew of its existence could only regard it as a wildcard of sorts, since success was far from being guaranteed. Therefore, the military campaign against Japan proceeded to prepare for an invasion of the Japanese home islands. By this time, Allied naval and air fleets were operating nearly unopposed, attacking targets of their choosing without facing significant opposition.

Naval Bombardments

On 14 Jul 1945, battleships South Dakota, Indiana, and Massachusetts bombarded Kamaishi, Honshu; the primary target was the Kamaishi Works of the Japan Iron Company. A small Japanese gunboat attempted to defend against the overwhelming American force. The escorting destroyers moved forth to fire at the small craft; due to either the small size of the target or inaccurate American aiming, several destroyer shells flew over the target and exploded in the town, killing civilians and causing fires. As the battleships opened fire on the iron work facilities, smoke from the burning civilian buildings periodically provided a smoke screen for the Japanese. Nevertheless, when the bombardment was completed, Japanese officials estimated that the damage done to the plants required about 65% of the total value of the physical assets to repair, and the repair would take 8 to 12 months to complete. Explosions at the iron works facilities killed many civilians, while nearby refrigeration and fishing industries were also damaged.

On 15 Jul, three Iowa-class battleships Iowa, Missouri, and Wisconsin bombarded industrial targets at Muroran, Hokkaido. The targets were the Wanishi Iron Works plants and the Muroran Works, both of the Japan Steel Company. Despite limited visibility, the successful bombardment caused damages amounting to the loss of about two and a half months of output of coke and a slightly smaller loss of pig iron for the Wanishi Iron Works, and 40% of a month's output for the Muroran Works. The bombardment also significantly disrupted railway, electric, and telephone systems.

On 17 Jul, battleships shelled Hitachi with a stunning count of 1,207 16-inch shells and 292 6-inch shells from light cruisers.

18 Jul, the North Carolina, Alabama, Iowa, Missouri, and Wisconsin of the US Navy and King George V of the British Navy bombarded Hitachi and surrounding areas, Honshu. Gunfire moderately damaged the Taga Works and Mito Works of Hitachi Manufacturing Company. The Yamate Plant and the copper refining plants of Hitachi Mine also received damages. Civilian targets were also bombarded, causing significant damage to housing sections as well as telephone, power, and water services. Fires spread quickly due to the lack of firefighters (already fled the city).

On 29 and 30 Jul, South Dakota, Indiana, Massachusetts bombarded Hamamatsu, Honshu, during the night. During this bombardment, high explosive and incendiary shells were used, causing widespread damage.

On 9 Aug, a day after the second atomic bomb was dropped on Nagasaki, South Dakota, Indiana, and Massachusetts conducted a second bombardment on Kamaishi, Honshu, destroying what was left from the first bombardment three weeks prior. Tally of shells fired would result to 850 16-inch shells from battleships, 1,440 8-inch shells from heavy cruisers, and a staggering 2,500 5-inch shells from supporting destroyers. If Akabane's observations in Jul were wrong, any remaining faith in Japan's ability to defend itself was crushed by Aug 1945.

Overall, during this period Allied ships fired 4,500 shells from battleships' primary weapons alone.

Aerial Attacks

As early as late 1944, American bombers began a bombing campaign against Japanese cities that killed as many as 500,000 by the end of the Pacific War. For more information on these bombings, please see the WW2DB article Bombing of Tokyo and Other Cities.

On 24 and 28 Jul, 1945, Task Force 38 under Admiral Halsey launched two carrier aircraft attacks against what was left of the Japanese fleet, which by now were confined to their home ports due to the combination of the lack of fuel as well as the near-total Allied air superiority. Most of the vessels were destroyed without being able to get underway, and marked the final destruction of the once proud fleet.

Effect on Japanese Morale

Between the naval blockades and aerial bombings, however willing to fight for their home islands, the Japanese morale was being shaken. Yutaka Akabane, a senior level civil servant, observed:

"It was the raids on the medium and smaller cities which had the worst effect and really brought home to the people the experience of bombing and a demoralization of faith in the outcome of the war.... It was bad enough in so large a city as Tokyo, but much worse in the smaller cities, where most of the city would be wiped out. Through May and June the spirit of the people was crushed. (When B-29s dropped propaganda pamphlets) the morale of the people sank terrifically, reaching a low point in July, at which time there was no longer hope of victory or draw but merely desire for ending the war."

The Invasion Plans

As the naval and air forces bombarded Japan, the Allied leaders planned the actual invasion, which was code named Operation Downfall. The responsibility of planning went to Douglas MacArthur, Chester Nimitz, George Marshall, Ernest King, Hap Arnold, and William Leahy. The inter-service rivalry between the US Army and US Navy was addressed by an agreement that, should situation deem necessary, US Army General Douglas MacArthur would assume total command. Regarding the Japanese capacity to defend the Japanese home islands, American planning assumed:

The invasion plan called for two separate invasions.

Operation Olympic was the sub-plan that targeted the Japanese home island of Kyushu. It was scheduled to take place on 1 Nov 1945, code named X-Day, with Okinawa acting as the primary staging area. The invasion fleet was to include 42 aircraft carriers, 24 battleships, and over 400 destroyers and destroyer escorts. The fleet would escort 14 American divisions, both Army and Marine Corps, that would form the initial assault force. The American forces were to conquer and hold the southern third of Kyushu. A deceptive operation, Operation Pastel, was to be launched against cities on the Chinese coast and Taiwan in support of Operation Olympic.

Operation Coronet was to take place on 1 Mar 1946, code named Y-Day, assuming Operation Olympic had successfully secured airfields so that additional land-based air support would be available. It was to be the largest amphibious operation in history, with 25 divisions participating in the initial invasion, including those in floating reserve; the great invasion force was to include those transferred from the recently-concluded European War. The invasion beaches were to be at Kujikuri on the Boso Peninsula and Hiratsuka at Sagami Bay, and the forces would work their way north across the Kanto plain toward Tokyo.

Because Japanese geography did not provide many invasion beaches, the Japanese organized a strong defense, particularly at Kyushu. Over 10,000 aircraft of various types and sizes were prepared as kamikaze aircraft. Underground networks of bunkers and caves stored food, water, and thousands of tons of ammunition. 2,350,000 regular soldiers and 250,000 garrison troops were deployed, 900,000 of which were stationed in Kyushu by Aug 1945. 32,000,000 militia, in other words all males between the age of 15 and 60 and all females between 17 and 45, were given the task to supplement the regular military; their weapons include everything from antique bronze cannons to Arisaka rifles, from bamboo spears to Model 99 light machine guns. Perhaps the eeriest fact was that after the war the United States discovered even children were trained to become suicide bombers when necessarily, strapping explosives around their torsos and rolling under the treads of American tanks. "This was the enemy the Pentagon had learned to fear and hate", said Dan van der Vat, "a country of fanatics dedicated to hara-kiri, determined to slay as many invaders as possible as they went down fighting". Although there was a strong dovish movement in Tokyo to end the war by seeking a conditional surrender, Ketsu-Go (Operation "Decision") continued to move forth, aiming to cause as much casualty as possible in order to sway American popular opinion. If they could cause more casualties than what the American people could accept, they thought, Japan might have a chance at negotiating for an armistice.

Naturally, the American plan considered Japanese resistance. It noted the possibility that the invasion "will be opposed not only by the available organized military forces of the Empire, but also by a fanatically hostile population", which would result in high casualties. In a study done by the United States Joint Chiefs of Staff in Apr 1945, at least 456,000 casualties were to be expected for Operation Olympic alone. Some other evaluations were also done, and their casualty estimates ranged anywhere from 30,000 to 1,000,000. In preparation, the United States manufactured 500,000 Purple Heart medals to award to those injured in combat.

Operation Downfall was never carried out. With the use of the atomic bombs and Russia's sudden declaration of war on Japan, WW2 in Asia ended without the need for the potentially costly invasion. At the date of this writing, over 100,000 of the Purple Heart medals still sat in American government warehouses.

Sources: American Caesar, Nihon Kaigun, Operational Experiences of Fast Battleships, the Pacific Campaign, Wikipedia.

Preparations for Invasion of Japan Interactive Map

Preparations for Invasion of Japan Timeline

15 Apr 1945 American carrier aircraft struck Japanese airfields in southern Kyushu, Japan while 300 US Army B-29 bombers conducted raids on Kawasaki and Tokyo.
25 May 1945 Operation Olympic, the invasion of Japan, was approved by the US Joint Chiefs of Staff, setting the date at 1 Nov 1945.
2 Jun 1945 American carrier aircraft of Task Force 38 attacked airfields in southern Kyushu, Japan. On the same day, 12 Japanese ships were sunk or damaged by naval mines in Japanese waters.
3 Jun 1945 American carrier aircraft of Task Force 38 attacked airfields in southern Kyushu, Japan for the second day in a row. On the same day, 7 Japanese ships were sunk or damaged by naval mines in Japanese waters.
8 Jul 1945 Over 100 American fighters struck eastern Honshu, Japan from their bases on Iwo Jima, Japan.
12 Jul 1945 A number of B-25 bombers based in Okinawa attacked military airfields on Kyushu, Japan.
14 Jul 1945 American battleships USS South Dakota, USS Indiana, and USS Massachusetts and escorting destroyers bombarded Kamaishi, Honshu, Japan; the primary target was the Kamaishi Works of the Japan Iron Company, but several destroyers shells overshot the target and hit the town, killing many civilians; battleship shells were more accurate, destroying about 65% of the industrial complex, but they also killed many civilians; this was the first time the Japanese home islands were subjected to naval bombardment. To the north, the sinking of 6 warships and 37 steamers on the ferry route between Honshu and Hokkaido effectively cut off the latter from the rest of the home islands. At Kure, aircraft of US Navy TF 38 damaged carrier Amagi, carrier Katsuragi, and battleship Haruna. Far to the south, the USAAF XXI Bomber Command canceled a long-range P-51 raid from Iwo Jima to attack Meiji and Kagamigahara near Nagoya due to poor weather.
15 Jul 1945 American battleships USS Iowa, USS Missouri, and USS Wisconsin bombarded industrial targets at Muroran, Hokkaido, Japan; the main targets were Wanishi Iron Works plants and the Muroran Works. From the air, American naval aircraft attacked northern Honshu and Hokkaido, destroying railways and coal ferries. 104 US Army P-51 fighters based in Iwo Jima Meiji, Kagamigahara, Kowa, Akenogahara, Nagoya, and Suzuko, Japan. B-24 bombers attacked Tomitaka, Usa, Kikaiga-shima, Amami Islands, Yaku-shima, Osumi Islands, and Tamega Island. After sun down, American B-29 bombers mined Japanese waters at Naoetsu and Niigata and Korean waters at Najin, Busan, and Wonsan, while other B-29 bombers attacked and seriously damaged the Nippon Oil Company facilities at Kudamatsu in southwestern Japan.
17 Jul 1945 UK Task Force 37 and US Task Force 38.2 launched their first strike on the Japanese home islands; it was the first British attack on Japan in the Pacific War. British Seafire carrier fighters were launched against Japanese airfields at Kionoke, Naruto, and Miyakawa. American warships bombarded Hitachi, Ibaraki Prefecture, Japan. 1,207 16-inch shells from battleships and 292 6-inch shells from cruisers were fired.
18 Jul 1945 American battleships USS North Carolina, USS Alabama, USS Iowa, USS Missouri, and USS Wisconsin and British battleship HMS King George V bombarded Hitachi, Ibaraki Prefecture, Japan with 2,000 shells; the Taga Works and Mito Works of Hitachi Manufacturing Company were moderately damaged, and the Yamate Plant and the copper refining plants of Hitachi Mine were lightly damaged. Civilian housing areas were also attacked, causing many deaths.
19 Jul 1945 US Navy Task Force 38 carrier aircraft damaged carrier Amagi, carrier Katsuragi, and battleship Haruna at Kure Naval Shipyard, Japan.
19 Jul 1945 US warships of Task Group 35.4 conducted a final bombardment of radar stations at Nojima Saki about 90 kilometers south of Tokyo, Japan.
20 Jul 1945 HMS Indefatigable joined UK Task Force 37 and US Task Force 38.2 for an attack on the Japanese home islands. On the same day, an US Army B-29 bomber failed to attack the Imperial Palace in Tokyo with a large "Pumpkin bomb".
24 Jul 1945 British TF 37 launched 416 sorties, 261 of which were sent against the Japanese home islands and 155 were for defensive patrols; escort carrier Kaiyo was damaged by British carrier planes. On the same day, American TF 38 launched 600 aircraft against Kure, Nagoya, Osaka, and Miho, sinking battleship-carrier Hyuga, heavy cruiser Tone, and target ship Settsu, and damaging carrier Ryuho, carrier Amagi, battleship-carrier Ise, battleship Haruna, heavy cruiser Aoba, light cruiser Oyodo, transport Kiyokawa Maru; the Aichi aircraft factories at Nagoya were seriously damaged.
24 Jul 1945 Settsu was attacked by 30 US Navy F6F-3 fighters while off Kure, Hiroshima, Japan after 1500 hours, suffering one direct bomb hit and five near misses. Captain Masanao Ofuji grounded her on the island of Etajima to prevent sinking.
25 Jul 1945 US carrier aircraft attacked Japanese shipping in the Inland Sea near Osaka and Nagoya, Japan.
28 Jul 1945 137 American P-47 aircraft based in Ie Shima, Okinawa, Japan attacked targest in Kyushu, Japan. On the same day, 471 B-29 bombers attacked smaller Japanese cities in the home islands with incendiary bombs. Finally, from the sea, US Navy TF 38 struck Inland Sea between Nagoya and northern Kyushu, sinking battleship Haruna, battleship-carrier Ise, heavy cruiser Aoba, and light cruiser Oyodo, and damaging carrier Katsuragi and carrier Hosho.
28 Jul 1945 While beached on the island of Etajima, Hiroshima, Japan, Settsu was attacked by 3 US Navy carrier aircraft, suffering two direct bomb hits.
29 Jul 1945 American battleships USS South Dakota, USS Indiana, and USS Massachusetts began a two-day bombardment of Hamamatsu, Shizuoka Prefecture, Japan.
30 Jul 1945 American battleships USS South Dakota, USS Indiana, and USS Massachusetts ended a two-day bombardment of Hamamatsu, Shizuoka Prefecture, Japan. Meanwhile, carrier fighters attacked airfields, railroads, and tactical targets in the Kobe-Osaka region.
4 Aug 1945 In a public statement, Douglas MacArthur announced that "a mighty invasion force is being forged", referring to the seemingly impending invasion of the Japanese home islands.
9 Aug 1945 258 British Avenger, Corsair, Hellcat, Firefly, and Seafire carrier aircraft of Task Force 37 expended more than 120 tons of bombs and cannon shells on targets in and near the Japanese home islands. Meanwhile, American battleships USS South Dakota, USS Indiana, and USS Massachusetts bombarded Kamaishi, Iwate, Japan. 850 16-inch shells from battleships, 1,440 8-inch shells from cruisers, and 2,500 5-inch shells from destroyers were fired.
1 Nov 1945 This date was the scheduled launch day for Operation Olympic, the invasion of Kyushu, Japan, which never took place.

Photographs

F4U-1D Corsair with Marine Squadron 216 aboard USS Wasp (Essex-class) being moved onto the deck-edge elevator on its way to the hangar deck following a strike against targets in and around Tokyo, Japan, Feb 17, 1945.Ground crewmen arming an FG-1D Corsair of Marine Fighting Squadron 312, the “Checkerboarders,” at Kadena airfield, Okinawa, Japan, Apr-Aug 1945TBM Avenger and SB2C Helldiver bombers dropped their load on the Japanese city of Hakodate, Jul 1945Battleship Indiana, battleship Massachusetts, and cruiser Quincy bombarding Kamaishi, Iwate, Japan, 14 Jul 1945
See all 15 photographs of Preparations for Invasion of Japan

Maps

Estimated Japanese troop depositions in Kyushu, Japan, 9 Jul 1945Map depicting the proposed invasion routes of Operation Downfall; Japanese defensive positions were as of Aug 1945Map depicting the proposed invasion routes of Operation OlympicEstimated Japanese troop depositions in Kyushu, Japan, 2 Aug 1945
See all 6 maps of Preparations for Invasion of Japan



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Visitor Submitted Comments

  1. gdh says:
    15 Jun 2005 05:31:57 AM

    during naval bombardments of one of these civilian centres, conflagration which followed was attributed (by Allies) to cooking fires upset by blast setting fire to paper houses.
  2. Danny says:
    8 Nov 2006 10:42:22 AM

    I am searching for information on my Uncle Daniel R. Berardinelli. ZI know he was shot down sometime in May to July 1945. I was named after him and have never been able to find out what took place in that battle.

    Thank you for your help. Danny
  3. Wayne VanDerVoort says:
    22 Jan 2007 04:23:02 PM

    You should also mention the other ships that accompanied Halseys battle ships. The cruisers USS Dayton and the USS Atlanta and the destroyers USS Norman Scott, USS Remey and the USS McGowan.
  4. Anonymous says:
    3 Mar 2007 12:10:19 AM

    Is there anything related to the Kamikaze Pilots
  5. David Adams says:
    16 Dec 2007 11:08:59 AM

    Thanks for your great and informative site.

    1st paragraph, last sentence, please should be pleased

    2nd paragraph, 3rd line, tha should be that

    3rd paragraph, loss about should read loss of about (add the word of)

    3rd paragraph from the bottom, (Japanese was not merely waiting) should read (Japanese were not merely waiting)
  6. Anonymous says:
    2 Feb 2008 08:44:32 PM

    AUG 28 1945 8 SHIPS ENTERED TOKEY BAY AS ADFANCE FORCE NOT KNOWING IF MINE FIELDS OR SHORE BATTERYS WERE STILL ACTIVE ALL WENT WELL THE FIRST DAY IN TOKEYO WE WERE ALONE AND THE RESIDANT WERE AFRAID NOT KNOWING WHAT TO EXPECT WITHIN DAYS DAYS MCARTHURS FORCE TOOK OVER AND THEY RELIZED THEY WERER SAFE THE FIST FEW DAYS MP WER SHORT AND WE WERE PULLED OF SHIPS AS SP WORKING WITH MP UNTIL THEY BUILT STRENTH VERY INTERESIN TIME DONT SEE MUCH ABOUT 28 ETERANCE OF HARBOR IST FORIN SHIPS TO ENTER SINCE ADMERL PERREY
  7. Chrysten says:
    28 May 2009 07:09:58 PM

    DANNY, PLEASE EMAIL ME @ chrysten@hotmail.com
    I HAVE INFORMATION ON YOUR UNCLE! HE WAS MY UNCLES PILOT.
  8. Anonymous says:
    24 Feb 2011 10:07:44 PM

    "100,000 are left at the date of this writing"
    would you please tell me that exact date
    much thanks
  9. Yvonne Blea says:
    22 Aug 2011 10:47:31 AM

    I found a flag with CO. B 130 Inf 33rd division with a bunch of signatures on it. This flag belonged to my uncle who served with the people
    The date was 6/25/45. It is a Japanese flag, it also has other numbers on it. any information would be appreciated, thanks Yvonne
  10. Anonymous says:
    29 Oct 2011 12:00:08 PM

    I am looking for any information on my dad Eldon Willard Beck who was a corporal in the US Marines. He was either in Iwo Jima or Okinawa. He was from Texas and was only 17 when he went into the Marines. Does any one remember him or know any thing about him. He never talk about what went on over there. He passed away about 17 years ago. Just wondered if any one remembered him.
  11. John Buss says:
    15 Apr 2012 11:25:37 PM

    There were a number of Allied POWs working as forced labor at industrial plants in Kawasaki, and throughout Japan, at the time of these bombings. It makes me wonder how many POW lives were lost with the two atomic bombs.
  12. Dee says:
    15 Sep 2012 03:18:18 AM

    I have just found out that my father was on the USS Makin Island. My understanding is he was a cook on board. Any information or photo would be appreciated. William S Person in 1944.
  13. Anonymous says:
    27 Oct 2012 11:40:10 AM

    You pathetic dog, an excuse of the human race how the hell would the planning of an invasion of Japan be linked to the Kamikaze pilots..... you useless brat.
  14. Anonymous says:
    13 May 2013 06:59:58 AM

    i like this passage
  15. Derek Chambers says:
    1 Nov 2013 01:23:50 PM

    I am very interested in the WW2 do you have any DVDS on this subject or books.

    Regardsa Derek Chambers

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More on Preparations for Invasion of Japan
Participants:
» Halsey, William
» Ito, Kiyoshi
» Kasai, Tomokazu

Location:
» Japan

Ship Participants:
» Alabama
» Alaska
» Amagi
» Aoba
» Arbiter
» Atlanta
» Belleau Wood
» Cowpens
» Essex
» Haruna
» Hornet (Essex-class)
» Hyuga
» Independence
» Indiana
» Intrepid
» Iowa
» Ise
» Kaiyo
» Katsuragi
» King George V
» Makin Island
» Missouri
» Nagato
» North Carolina
» Oyodo
» San Jacinto
» Settsu
» South Dakota
» Ticonderoga
» Tone
» Victorious
» Washington
» Wisconsin

Related Book:
» American Caesar: Douglas MacArthur 1880-1964


Preparations for Invasion of Japan Photo Gallery
F4U-1D Corsair with Marine Squadron 216 aboard USS Wasp (Essex-class) being moved onto the deck-edge elevator on its way to the hangar deck following a strike against targets in and around Tokyo, Japan, Feb 17, 1945.
See all 15 photographs of Preparations for Invasion of Japan



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"Since peace is now beyond hope, we can but fight to the end."

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