From
http://www.ww2pacific.com/downfal0.html World War II in the Pacific
Operation Downfall
The Invasion of Japan
Operation DOWNFALL, the invasion of Japan, was in two components scheduled for the Fall and Spring of 1945-46:
Operation OLYMPIC, Nov 1, 1945, after the hurricane season, before winter. General Krueger, Sixth Army, with nine divisions (3 more in reserve) was to invade three beaches in southern Kyushu, the southern-most of the four Japanese home islands. This was to became a giant airbase to support the next invasion phase in the Spring of 1946. The Japanese had correctly predicted our invasion point and had reinforced Kyushu threefold over initial US expectations.
Operation CORONET, March 1, 1946, of Honshu, the main island, with 22 divisions in the Spring after air fields on Kyushu allowed landbased air support. There were to be two prongs:
General Hodges, with the 1st Army to land east of Tokyo, clear the peninsula, establish air fields, land tank divisions transferred from European, about 30 days, then charge across the plains to take the capital.
Ten days after the initial landing, LtGen Eichelberger with 8th Army was to attack west of Yokohama, Tokyo's seaport, open Tokyo Bay and block any reinforcement of Tokyo.
U.S. PREPARATIONS
The previous phase of the war had been the capture of the Marshalls --Saipan, Tinian and the US island of Guam during June, July and Aug 1944. These were captured to provide air fields within the effective range of B-29 Superfortress, very heavy bombers. Previous attempts to fly B-29s from inland China could only reach the southern portions of Japan with minimal bomb loads and required an impossible to maintain rate of logistics. B-29 attacks started in November 1944, by March 1945, Tokyo, Osaka and other industrial cities had been bombed
Iwo Jima was taken in Feb-March 1945 to provide an intermediate airstrip for damaged B-29s, for fighter escorts, and for shorter ranged B-24 Liberator heavy bombers. Air attack was ratcheted up to 300 plane raids and the attack method changed from explosives to incendiary in which 15% of Tokyo was destroyed in the first raid.1
Air dropped mining began in March 1945 in the Shimonoseki Straight, separating Kyushu and Honshu, to isolate the invasion island. Over 120 ships succumb to these mines.
Submarine efforts were concentrated in the Sea of Japan, on the northwest coast, while carrier task forces concentrated on the Pacific Ocean side.
Preparation for the invasion began with the Okinawa campaign. This is the largest island in the Ryukuyu Islands, the chain nearest to Japan. The native Okinawans were of Chinese extraction but had been an independent kingdom for 800 years until Japan invaded in 1875. Annexed, they continued a race apart, looked down upon my Japanese.2
Carrier Task Forces. The first strike on Japan's home islands was the period 18-22March 1945 to disrupt attacks on our invasion fleet as it approached Okinawa. Raids by 11 fleet carriers and 6 light carriers destroyed aircraft such that the Japanese air attacks on Okinawa were delayed until 6 days after the landings.
Remnants of the Imperial Navy were destroyed in their yards at Kure (near Hiroshima) on the main island of Honshu during early July.
Two fleets were to participate in Olympic: The Strike fleet with 21 carriers, 10 fast battleships and their train. The Assault fleet had 1,500 transports and 800 warships including 26 carriers and 13 battleships.
Operation Zipper by Lord Mountbatten's southeast Asia command was to take Singapore and the Malay Peninsula about 1Sept45. Also, the US China theater was planning to take the Liuchow Peninsula, west of Hong Kong, in mid-August as a port to supply China.
JAPANESE DEFENSES
Troops. Japan was scrapping the bottom of a big barrel. Two million new recruits were called up and experienced Armies was brought back from China and Manchuria to defend the homeland.
Kamikaze. Numbers of about 2000 Navy and 3500 Army airplanes have been cited as available for the defense, and of course, preparations would have continued with 500 mini-subs under construction, specially designed aircraft build, motor boat and manned torpedo stations established. Japanese military was committed to and was convinced they could repel the initial assault. That we might make as second assault was too much to consider. 1,465 Kamikaze had attacked at Okinawa, 400 miles away, had sunk or damaged 250 warships. A ratio of 1 hit per 6 attempts. Troopships sailing into waters adjacent to Japan, they thought, didn't stand a chance. US planners estimated 250 hits; Japanese planners expected 480 ships sunk. See suicide page for a range of special attack (suicide) weapons used by the Japanese.
Expected casualties. By this stage in the war, the overwhelming American material condition had reduced the ratio of American killed vs. enemy. The assault by Pacific trained Army troops from the Philippine Campaign and combat hardened Marines lessened the expected causalities on the American side. Conversely, first rate Japanese troops with pre-war combat experience in China -- which had made the initial conquests in the Pacific against inexperienced Allied troops -- had mostly been killed. The combat trained troops in China had been replaced with secondary troops -- these now experienced troops were recalled to defend the home islands. These troops had never been exposed in China to the massive air attacks that were now normal operations from US land and sea forces. Japan's naval ships had been destroyed. Japan had never had an adequate new pilot training program. Industrial resupply was dramatically weakened with every war facility destroyed as soon as it was discover by American air reconnaissance. Raw materials had been cut off as the merchant marine was destroyed by American submarines and aircraft.
Usually omitted from the statistics, however, because the atomic bomb was a secret, is the 300,000 white slave laborers held by Japan. Most of these were to be executed if the invasion had happened. The appearance of the atomic bomb brought such a sudden end to the war, that these lives were saved, along with the expected military casualties of both sides and massive numbers of Japanese civilian population either participating in the defense or as collateral damage.
Prospects of Operation Olympic. Japan fully expected to be able to repel the first landing with the help of suicide tactics. As shown at Normandy, the Americans expected to overpower all in their way. The U.S. expected to have air superiority, which places an imposition on the defense. The Navy expected to interdict all movements of resupply and reinforcement.
Best guess, the attack would be a repeat of "bloody Omaha beach" with a successful American landing. The plan called for sealing the mountains rather than fighting an Okinawa type campaign. The goal of establishing air bases would proceed as an American specialty. There would be continued casualties, but the goal accomplished.
CORONET . With American aircraft numbers measured in the 5-digits by aircraft type, and Japan's total aircraft numbers measured in the 4-digits, possibly 3-or 2-digits after Olympic, it is inconceivable why Coronet should happen. Japan could be allowed to suffocate under a siege with sea and air attack. No item of military importance would exist within 10 miles of the shore or any item that could be seen from the air. However, if Japan had persisted, it could only be because of great resistance at Kyushu. The momentum of war would have followed the plan. Invasion of Honshu would have been brutal with total destruction of every square yard before the troops and ruthless combat. The atomic bomb not only saved many Japanese lives, it may have saved the nation. With surrender, the occupying troops could be magnanimous in the American manner. If they had to fight fanatical resistance, they would have been compelled to destroy everything in sight as a potential military threat.
Admiral William D. Leahy. 5-star admiral, president of the US Joint Chiefs of Staff and the combined American-British Chiefs of Staff, and chief of staff to the commander-in-chief of the army and navy from 1942–1945 (Roosevelt) and 1945–1949 (Truman):
"It is my opinion that the use of this barbarous weapon at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender. . . . My own feeling was that in being the first to use it, we had adopted the ethical standard common to the barbarians of the Dark Ages. I was not taught to make war in that fashion, and wars cannot be won by destroying women and children."
Fleet Admiral Chester W. Nimitz, commander in chief of the Pacific Fleet, quoted by his widow:
". . . I felt that it was an unnecessary loss of civilian life. . . . We had them beaten. They hadn't enough food, they couldn't do anything." And – E. B. Potter, naval historian wrote: "Nimitz considered the atomic bomb somehow indecent, certainly not a legitimate form of warfare."
Admiral William "Bull" Halsey, commander of the Third Fleet:
"The first atomic bomb was an unnecessary experiment. . . . It was a mistake ever to drop it . . . (the scientists) had this toy and they wanted to try it out, so they dropped it. . . . It killed a lot of Japs, but the Japs had put out a lot of peace feelers through Russia long before."
Rear Admiral Richard Byrd:
"Especially it is good to see the truth told about the last days of the war with Japan. . . . I was with the Fleet during that period; and every officer in the Fleet knew that Japan would eventually capitulate from . . . the tight blockade."
Rear Admiral Lewis L. Strauss, special assistant to the Secretary of the Navy:
"I, too, felt strongly that it was a mistake to drop the atom bombs, especially without warning." [The atomic bomb] "was not necessary to bring the war to a successful conclusion . . . it was clear to a number of people . . . that the war was very nearly over. The Japanese were nearly ready to capitulate . . . it was a sin – to use a good word – [a word that] should be used more often – to kill non-combatants. . . ."
Major General Curtis E. LeMay, US Army Air Forces (at a press conference, September 1945):
"The war would have been over in two weeks without the Russians entering and without the atomic bomb . . . the atomic bomb had nothing to do with the end of the war at all."
Major General Claire Chennault, founder of the Flying Tigers, and former US Army Air Forces commander in China:
"Russia's entry into the Japanese war was the decisive factor in speeding its end and would have been so even if no atomic bombs had been dropped..."
Henry H. "Hap" Arnold, Commanding General of the US Army Air Forces.
". . . [F]rom the Japanese standpoint the atomic bomb was really a way out. The Japanese position was hopeless even before the first atomic bomb fell. . . ."
Lieutenant General Ira C. Eaker, Arnold's deputy.
"Arnold's view was that it (dropping the atomic bomb) was unnecessary. He said that he knew that the Japanese wanted peace. There were political implications in the decision and Arnold did not feel it was the military's job to question it. . . . I knew nobody in the high echelons of the Army Air Force who had any question about having to invade Japan."
Arnold, quoted by Eaker:
"When the question comes up of whether we use the atomic bomb or not, my view is that the Air Force will not oppose the use of the bomb, and they will deliver it effectively if the Commander in Chief decides to use it. But it is not necessary to use it in order to conquer the Japanese without the necessity of a land invasion."
General George C. Kenney, commander of Army Air Force units in the Southwest Pacific, when asked whether using the atomic bomb had been a wise decision.
"No! I think we had the Japs licked anyhow. I think they would have quit probably within a week or so of when they did quit."
W. Averill Harriman, in private notes after a dinner with General Carl "Tooey" Spaatz (commander in July 1945 of the Pacific-based US Army Strategic Air Forces), and Spaatz's one-time deputy commanding general in Europe, Frederick L. Anderson:
"...Both felt Japan would surrender without use of the bomb, and neither knew why a second bomb was used."
General Dwight D. Eisenhower:
"I voiced to him (Secretary of War Henry L. Stimson ed note: a Stalinist spy) my grave misgivings, first on the basis of my belief that Japan was already defeated and that dropping the bomb was completely unnecessary, and secondly because I thought that our country should avoid shocking world opinion by the use of a weapon whose employment was, I thought, no longer mandatory as a measure to save American lives. It was my belief that Japan was at that very moment seeking some way to surrender with a minimum of loss of 'face'. . . . It wasn't necessary to hit them with that awful thing."
former President Herbert Hoover:
"I told MacArthur of my memorandum of mid-May 1945 to Truman, that peace could be had with Japan by which our major objectives would be accomplished. MacArthur said that was correct and that we would have avoided all of the losses, the Atomic bomb, and the entry of Russia into Manchuria."
Richard M. Nixon:
"MacArthur once spoke to me very eloquently about it. . . . He thought it a tragedy that the Bomb was ever exploded. MacArthur believed that the same restrictions ought to apply to atomic weapons as to conventional weapons, that the military objective should always be to limit damage to noncombatants. . . . MacArthur, you see, was a soldier. He believed in using force only against military targets, and that is why the nuclear thing turned him off, which I think speaks well of him
Norman Cousins, from an interview with MacArthur:
". . . [H]e saw no military justification for the dropping of the bomb. The war might have ended weeks earlier, he said, if the United States had agreed, as it did later anyway, to the retention of the institution of the emperor."