Operation Downfall was the proposed Allied plan for the invasion of the Japanese home islands near the

end of World War II End of World War II can refer to: * End of World War II in Europe * End of World War II in Asia {{set index Since Japan and the Soviet Union maintained a state of wary neutrality until the Soviet declaration of war on Japan in August 1945, Japanese observers based in Japanese-held territories in Manchuria, Korea, Sakhalin, and the Kuril Islands constantly watched the port of

Vladivostok Vladivostok ( rus, Владивосто́к, a=Владивосток.ogg, p=vɫədʲɪvɐˈstok) is the largest city and the administrative center of Primorsky Krai, Russia. The city is located around the Golden Horn Bay on the Sea of Japan, ...

and other seaports in the Soviet Union. According to Thomas B. Allen and

Norman Polmar Norman Polmar is a prominent author specializing in the naval, aviation, and intelligence areas. He has led major projects for the U.S. Department of Defense and the U.S. Navy, and foreign governments. His professional expertise has served three ...

, the Soviets had carefully drawn up detailed plans for the Far East invasions, except that the landing for Hokkaido "existed in detail" only in Stalin's mind and that it was "unlikely that Stalin had interests in taking Manchuria and even taking on Hokkaido. Even if he wanted to grab as much territory in Asia as possible, he was too much focused on establishing a beachhead in Europe more so than Asia."

Estimated casualties

Because the U.S. military planners assumed "that operations in this area will be opposed not only by the available organized military forces of the Empire, but also by a fanatically hostile population", high casualties were thought to be inevitable, but nobody knew with certainty how high. Several estimates were made, but varied widely in numbers, assumptions and purposes, which included advocating and opposing the invasion. The estimated casualty figures later became a crucial point in postwar

debate over the atomic bombings of Hiroshima and Nagasaki Substantial debate exists over the ethical, legal, and military aspects of the atomic bombings of Hiroshima and Nagasaki on 6 August and 9 August 1945 at the close of World War II (1939–45). On 26 July 1945, United States President Harry ...

. On 15 January 1945, the U.S. Army Service Forces released a document, "Redeployment of the United States Army after the Defeat of Germany." In it, they estimate that during the 18 month period after June 1945 (that is, through December 1946), the Army would be required to furnish replacements for 43,000 dead and evacuated wounded every month. From analysis of the replacement schedule and projected strengths in overseas theaters, it suggested that Army losses alone in those categories, excluding the Navy and Marine Corps, would be approximately 863,000 through the first part of 1947, of whom 267,000 would be killed or missing. This likewise excludes wounded who would be treated in-theater during an initial window of 30 days, later to be expanded to 120 days. In preparation for Operation Olympic, the invasion of southern Kyushu, various figures and organizations made casualty estimates based on the terrain, strength, and disposition of known Japanese forces. However, as reported Japanese strength in the Home Islands continued to climb and Japanese military performance increased, so too did the casualty estimates. In April 1945, the Joint Chiefs of Staff formally adopted a planning paper giving a range of possible casualties based on experience in both Europe and the Pacific. These ranged from 0.42 dead and missing and 2.16 total casualties per 1000 men per day under the "European Experience" to 1.95 dead and missing and 7.45 total casualties per 1000 men per day under the "Pacific Experience." This assessment included neither casualties suffered ''after'' the 90-day mark (US planners envisioned switching to the tactical ''defensive'' by X+120), nor personnel losses at sea from Japanese air attacks. In order to sustain the campaign on Kyushu, planners estimated a replacement stream of 100,000 men per month would be necessary, a figure achievable even after the partial demobilization following the defeat of Germany. As time went on, other US leaders made estimates of their own: In a letter to General Curtis LeMay when LeMay assumed command of the B-29 force on Guam, General

Lauris Norstad Lauris Norstad (March 24, 1907 – September 12, 1988) was an American general officer in the United States Army and United States Air Force. Early life and military career Lauris Norstad was born in Minneapolis, Minnesota to a Norwegian imm ...

told LeMay that if an invasion took place, it would cost the US "half a million" dead. In May, Admiral Nimitz's staff estimated 49,000 U.S casualties in the first 30 days of Operation Olympic, including 5,000 at sea. A study done by General MacArthur's staff in June estimated 23,000 US casualties in the first 30 days of Olympic and 125,000 after 120 days, fighting an assumed Japanese force of 300,000 (in actuality some 917,000 Japanese troops were on Kyushu,). When these figures were questioned by General Marshall, MacArthur submitted a revised estimate of 105,000, in part by deducting wounded men able to return to duty. In a conference with President Truman on June 18, Marshall, taking the Battle of Luzon as the best model for Olympic, thought the Americans would suffer 31,000 casualties in the first 30 days and ultimately 20% of Japanese casualties, which he estimated would include the entire Japanese force. This implied a total of 70,000 American casualties in the battle of Kyushu using the June projection of 350,000 Japanese defenders. Admiral Leahy, more impressed by the Battle of Okinawa, thought the American forces would suffer a 35% casualty rate (implying an ultimate toll of 268,000). Admiral King thought that casualties in the first 30 days would fall between Luzon and Okinawa, i.e., between 31,000 and 41,000. Of these estimates, only Nimitz's included losses of the forces at sea, though kamikazes had inflicted 1.78 fatalities and a similar number of wounded per kamikaze pilot in the Battle of Okinawa, and troop transports off Kyūshū would have been much more exposed. In July MacArthur's Intelligence Chief, Maj. Gen. Charles A. Willoughby, warned of between 210,000 and 280,000 battle casualties in the push to the "stop line" one-third of the way up Kyushu. Even when rounded down to a conservative 200,000, this figure implied a total of nearly 500,000 all-causes losses, of whom perhaps 50,000 might return to duty after light to moderate care. The US Sixth Army, the formation tasked with carrying out the major land fighting on Kyushu, estimated a figure of 394,859 casualties serious enough to be permanently removed from unit roll calls during the first 120 days on Kyushu, barely enough to avoid outstripping the planned replacement stream. Secretary of War Henry L. Stimson stated "We shall in my opinion have to go through an even more bitter finish fight than in Germany. We shall incur the losses incident to such a war and we shall leave the Japanese islands even more thoroughly destroyed than was the case with Germany." From

D-Day The Normandy landings were the landing operations and associated airborne operations on Tuesday, 6 June 1944 of the Allied invasion of Normandy in Operation Overlord during World War II. Codenamed Operation Neptune and often referred to as ...

V-E Day Victory in Europe Day is the day celebrating the formal acceptance by the Allies of World War II of Germany's unconditional surrender of its armed forces on Tuesday, 8 May 1945, marking the official end of World War II in Europe in the Easte ...

, the Western Allies alone suffered some 766,294 casualties. A study done for Stimson's staff by

William Shockley William Bradford Shockley Jr. (February 13, 1910 – August 12, 1989) was an American physicist and inventor. He was the manager of a research group at Bell Labs that included John Bardeen and Walter Brattain. The three scientists were jointl ...

estimated that invading Japan would cost 1.7–4 million American casualties, including 400,000–800,000 fatalities, and five to ten million Japanese fatalities. The key assumption was large-scale participation by civilians in the defense of Japan. Japanese military directives ordered the execution of all POWs being held if Japan was ever invaded. Towards the end of the war about 100,000 Allied prisoners were in Japanese custody. Outside the government, well-informed civilians were also making guesses. Kyle Palmer, war correspondent for the ''

Los Angeles Times The ''Los Angeles Times'' (abbreviated as ''LA Times'') is a daily newspaper that started publishing in Los Angeles in 1881. Based in the LA-adjacent suburb of El Segundo since 2018, it is the sixth-largest newspaper by circulation in the ...

'', said half a million to a million Americans would die by the end of the war.

Herbert Hoover Herbert Clark Hoover (August 10, 1874 – October 20, 1964) was an American politician who served as the 31st president of the United States from 1929 to 1933 and a member of the Republican Party, holding office during the onset of the Gre ...

, in memorandums submitted to Truman and Stimson, also estimated 500,000 to 1,000,000 fatalities, which were believed to be conservative estimates; however, it is not known if Hoover discussed these specific figures in his meetings with Truman. The Chief of the Army Operations Division thought them "entirely too high" under "our present plan of campaign." The Battle of Okinawa was one of the bloodiest in the Pacific, with an estimated total of over 82,000 direct casualties on both sides: 14,009 Allied deaths and 77,417 Japanese soldiers.Okinawa Prefecture. ''The Cornerstone of Peace: Number of Names Inscribed''. http://www.pref.okinawa.jp/site/kodomo/heiwadanjo/heiwa/7812.html (accessed February 4, 2017) Allied grave registration forces counted 110,071 dead bodies of Japanese soldiers, but this included conscripted Okinawans wearing Japanese uniforms. 149,425

Okinawans The Ryukyuan people ( ryu, 琉球民族 (るーちゅーみんずく), Ruuchuu minzuku or ryu, どぅーちゅーみんずく, Duuchuu minzuku, label=none, ja, 琉球民族/りゅうきゅうみんぞく, Ryūkyū minzoku, also Lewchewan or L ...

were killed, committed suicide or went missing, which was one-half of the estimated pre-war local population of 300,000. The Battle resulted in 72,000 US casualties in 82 days, of whom 12,510 were killed or missing (this figure excludes the several thousand US soldiers who died after the battle indirectly, from their wounds). The entire island of Okinawa is . If the US casualty rate during the invasion of Japan had been only 5% as high per unit area as it was at Okinawa, the US would still have lost 297,000 soldiers (killed or missing). In evaluating these estimates, especially those based on projected Japanese troop strength (such as General MacArthur's), it is important to consider what was known about the state of Japanese defenses at the time, as well as the actual condition of those defenses (MacArthur's staff believed Japanese manpower on Kyushu to be roughly 300,000).The Final Months of the War with Japan.
Retrieved 23 August 2015 Nearly 500,000

Purple Heart The Purple Heart (PH) is a United States military decoration awarded in the name of the President to those wounded or killed while serving, on or after 5 April 1917, with the U.S. military. With its forerunner, the Badge of Military Merit, ...

medals (awarded for combat casualties) were manufactured in anticipation of the casualties resulting from the invasion of Japan; the number exceeded that of all American military casualties of the 65 years following the end of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

, including the Korean and

Vietnam War The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...

s. In 2003, there were still 120,000 of these Purple Heart medals in stock. There were so many left that combat units in

Iraq Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq ...

and

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is borde ...

were able to keep Purple Hearts on hand for immediate award to soldiers wounded in the field.

Available equipment for defenders

Following the surrender and demobilization of Japan, vast amounts of war

matériel Materiel (; ) refers to supplies, equipment, and weapons in military supply-chain management, and typically supplies and equipment in a commercial supply chain context. In a military context, the term ''materiel'' refers either to the specif ...

were turned over to the US occupation forces in the Japanese Home Islands and South Korea. While some totals (particularly for items such as swords and small arms) may be inexact because of the problems of collection and the activities of the black market, the amount of military equipment available to the Japanese in and around the Home Islands by August 1945 was roughly as follows:

References

Notes

Bibliography

* * * * * * * * * * * * * * * * * * * * *

External links

* Allen, Thomas B., "
Operation Downfall
'". Houghton Mifflin Reader's Companion to Military History. * Bauer, K. Jack, "
Operation Downfall: Olympic, Coronet
World War II in the Pacific, The Invasion of Japan''". ww2pacific.com. * * . * Hoyt, Austin, '' American Experience'':
Victory in the Pacific
''; PBS documentary. * Japanese Monograph No. 23,
Waiting for the invasion
(notes on Japanese preparations for an American invasion) * Pearlman, Michael D.,
''Unconditional Surrender, Demobilization, and the Atomic Bomb''
; Combat Studies Institute, U.S. Army Command and General Staff College, 1996. * . {{DEFAULTSORT:Downfall Japan campaign World War II operations and battles of the Pacific theatre Cancelled invasions Operation Downfall Cancelled military operations of World War II Cancelled military operations involving the United States Cancelled military operations involving the United Kingdom United States Marine Corps in World War II Military operations of World War II