Deep in the recesses of the National Archives in Washington, D.C., hidden for nearly four decades lie thousands of pages of yellowing and dusty documents stamped "Top Secret". These documents, now declassified, are the plans for Operation Downfall, the invasion of Japan during World War II. Only a few Americans in 1945 were aware of the elaborate plans that had been prepared for the Allied Invasion of the Japanese home islands. Even fewer today are aware of the defenses the Japanese had prepared to counter the invasion had it been launched.
Operation Downfall was finalized during the spring and summer of 1945.
It called for two massive military undertakings to be carried out in succession and aimed at the heart of the Japanese Empire.
In the first invasion - code named "Operation Olympic"- American combat troops would land on Japan by amphibious assault during the early morning hours of November 1, 1945 - 61 years ago. Fourteen combat divisions of soldiers and Marines would land on heavily fortified and defended Kyushu, the southernmost of the Japanese home islands, after an unprecedented naval and aerial bombardment.
The second invasion on March 1, 1946 - code named "Operation Coronet"-would send at least 22 divisions against 1 million Japanese defenders on the main island of Honshu and the Tokyo Plain.
It's goal: the unconditional surrender of Japan. With the exception of a part of the British Pacific Fleet, Operation Downfall was to be a strictly American operation. It called for using the entire Marine Corps, the entire Pacific Navy, elements of the 7th Army Air Force, the 8 Air Force (recently redeployed from Europe), 10th Air Force and the American Far Eastern Air Force. More than 1.5 million combat soldiers, with 3 million more in support or more than 40% of all servicemen still in uniform in 1945 - would be directly involved in the two amphibious assaults.
Casualties were expected to be extremely heavy.
Admiral William Leahy estimated that there would be more than 250,000 Americans killed or wounded on Kyushu alone. General Charles Willoughby, chief of intelligence for General Douglas MacArthur, the Supreme Commander of the Southwest Pacific, estimated American casualties would be one million men by the Fall of 1946. Willoughby's own intelligence staff considered this to be a conservative estimate.
During the summer of 1945, America had little time to prepare for such an endeavor, but top military leaders were in almost unanimous agreement that an invasion was necessary. While naval blockade and strategic bombing of Japan was considered to be useful, General MacArthur, for instance, did not believe a blockade would bring about an unconditional surrender. The advocates for invasion agreed that while a naval blockade chokes, it does not kill; and though strategic bombing might destroy cities, it leaves whole armies intact.
So on May 25, 1945, the Joint Chiefs of Staff, after extensive deliberation, issued to General MacArthur, Admiral Chester Nimitz, and Army Air Force General Henry Arnold, the top secret directive to proceed with the invasion of Kyushu. The target date was after the typhoon season.
President Truman approved the plans for the invasions July 24. Two days later, the United Nations issued the Potsdam Proclamation, which called upon Japan to surrender unconditionally or face total destruction.
Three days later, the Japanese governmental news agency broadcast to the world that Japan would ignore the proclamation and would refuse to surrender. During this same period it was learned -- via monitoring Japanese radio broadcasts -- that Japan had closed all schools and mobilized its school children, was arming its civilian population and was fortifying caves and building underground defenses.
Operation Olympic called for a four pronged assault on Kyushu. Its purpose was to seize and control the southern one-third of that island and establish naval and air bases, to tighten the naval blockade of the home islands, to destroy units of the main Japanese army and to support the later invasion of the Tokyo Plain. The preliminary invasion would began October 27 when the 40th Infantry Division would land on a series of small islands west and southwest of Kyushu. At the same time, the 158th Regimental Combat Team would invade and occupy a small island 28 miles south of Kyushu. On these islands, seaplane bases would be established and radar would be set up to provide advance air warning for the invasion fleet, to serve as fighter direction centers for the carrier-based aircraft and to provide an emergency anchorage for the invasion fleet, should things not go well on the day of the invasion.
As the invasion grew imminent, the massive firepower of the Navy – the Third and Fifth Fleets -- would approach Japan. The Third Fleet, under Admiral William "Bull" Halsey, with its big guns and naval aircraft, would provide strategic support for the operation against Honshu and Hokkaido. Halsey's fleet would be composed of battleships, heavy cruisers, destroyers, dozens of support ships and three fast carrier task groups. From these carriers, hundreds of Navy fighters, dive bombers and torpedo planes would hit targets all over the island of Honshu. The 3,000 ship Fifth Fleet, under Admiral Raymond Spruance, would carry the invasion troops.
Several days before the invasion, the battleships, heavy cruisers and destroyers would pour thousands of tons of high explosives into the target areas. They would not cease the bombardment until after the land forces had been launched.
During the early morning hours of November 1, the invasion would begin. Thousands of soldiers and Marines would pour ashore on beaches all along the eastern, southeastern, southern and western coasts of Kyushu. Waves of Helldivers, Dauntless dive bombers, Avengers, Corsairs, and Hellcats from 66 aircraft carriers would bomb, rocket and strafe enemy defenses, gun emplacements and troop concentrations along the beaches.
The Eastern Assault Force consisting of the 25th, 33rd, and 41st Infantry Divisions, would land near Miyaski, at beaches called Austin, Buick, Cadillac, Chevrolet, Chrysler, and Ford, and move inland to attempt to capture the city and its nearby airfield. The Southern Assault Force, consisting of the 1st Cavalry Division, the 43rd Division
and Americal Division would land inside Ariake Bay at beaches labeled
DeSoto, Dusenberg, Essex, Ford, and Franklin and attempt to capture
Shibushi and the city of Kanoya and its airfield.
On the western shore of Kyushu, at beaches Pontiac, Reo, Rolls Royce, Saxon, Star, Studebaker, Stutz, Winston and Zephyr, the V Amphibious Corps would land the 2nd, 3rd, and 5th Marine Divisions, sending half of its force inland to Sendai and the other half to the port city of Kagoshima.
On November 4, the Reserve Force, consisting of the 81st and 98th Infantry Divisions and the 11th Airborne Division, after feigning an attack on the island of Shikoku, would be landed -- if not needed elsewhere -- near Kaimondake, near the southernmost tip of Kagoshima Bay, at the beaches designated Locomobile, Lincoln, LaSalle, Hupmobile, Moon, Mercedes, Maxwell, Overland, Oldsmobile, Packard, and Plymouth.
Olympic was not just a plan for invasion, but for conquest and occupation as well. It was expected to take four months to achieve its objective, with the three fresh American divisions per month to be landed in support of that operation if needed. If all went well with Olympic, Coronet would be launched March 1,1946. Coronet would be twice the size of Olympic, with as many as 28 divisions landing on Honshu.
All along the coast east of Tokyo, the American 1st Army would land the 5th, 7th, 27th, 44th, 86th, and 96th Infantry Divisions, along with the 4th and 6th Marine Divisions. At Sagami Bay, just south of Tokyo, the entire 8th and 10th Armies would strike north and east to clear the long western shore of Tokyo Bay and attempt to go as far as Yokohama.
The assault troops landing south of Tokyo would be the 4th, 6th, 8th, 24th, 31st, 37th, 38th, and 8th Infantry Divisions, along with the 13th and 20th Armored Divisions.
Following the initial assault, eight more divisions - the 2nd, 28th, 35th, 91st, 95th, 97th, and 104th Infantry Divisions and the 11th Airborne Division -- would be landed. If additional troops were needed, as expected, other divisions redeployed from Europe and undergoing training in the United States would be shipped to Japan in what was hoped to be the final push.
Captured Japanese documents and post war interrogations of Japanese
military leaders disclose that information concerning the number of
Japanese planes available for the defense of the home islands was
dangerously in error. During the sea battle at Okinawa alone, Japanese
Kamikaze aircraft sank 32 Allied ships and damaged more than 400 others.
But during the summer of 1945, American top brass concluded that the
Japanese had spent their air force since American bombers and fighters
daily flew unmolested over Japan.
What the military leaders did not know was that by the end of July the Japanese had been saving all aircraft, fuel, and pilots in reserve, and had been feverishly building new planes for the decisive battle for their homeland. As part of Ketsu-Go, the name for the plan to defend Japan -- the Japanese were building 20 suicide takeoff strips in southern Kyushu with underground hangars. They also had 35 camouflaged airfields and nine seaplane bases.
On the night before the expected invasion, 50 Japanese seaplane bombers, 100 former carrier aircraft and 50 land based army planes were to be launched in a suicide attack on the fleet. The Japanese had 58 more airfields in Korea, western Honshu and Shikoku, which also were to be used for massive suicide attacks.
(con't)
Operation Downfall was finalized during the spring and summer of 1945.
It called for two massive military undertakings to be carried out in succession and aimed at the heart of the Japanese Empire.
In the first invasion - code named "Operation Olympic"- American combat troops would land on Japan by amphibious assault during the early morning hours of November 1, 1945 - 61 years ago. Fourteen combat divisions of soldiers and Marines would land on heavily fortified and defended Kyushu, the southernmost of the Japanese home islands, after an unprecedented naval and aerial bombardment.
The second invasion on March 1, 1946 - code named "Operation Coronet"-would send at least 22 divisions against 1 million Japanese defenders on the main island of Honshu and the Tokyo Plain.
It's goal: the unconditional surrender of Japan. With the exception of a part of the British Pacific Fleet, Operation Downfall was to be a strictly American operation. It called for using the entire Marine Corps, the entire Pacific Navy, elements of the 7th Army Air Force, the 8 Air Force (recently redeployed from Europe), 10th Air Force and the American Far Eastern Air Force. More than 1.5 million combat soldiers, with 3 million more in support or more than 40% of all servicemen still in uniform in 1945 - would be directly involved in the two amphibious assaults.
Casualties were expected to be extremely heavy.
Admiral William Leahy estimated that there would be more than 250,000 Americans killed or wounded on Kyushu alone. General Charles Willoughby, chief of intelligence for General Douglas MacArthur, the Supreme Commander of the Southwest Pacific, estimated American casualties would be one million men by the Fall of 1946. Willoughby's own intelligence staff considered this to be a conservative estimate.
During the summer of 1945, America had little time to prepare for such an endeavor, but top military leaders were in almost unanimous agreement that an invasion was necessary. While naval blockade and strategic bombing of Japan was considered to be useful, General MacArthur, for instance, did not believe a blockade would bring about an unconditional surrender. The advocates for invasion agreed that while a naval blockade chokes, it does not kill; and though strategic bombing might destroy cities, it leaves whole armies intact.
So on May 25, 1945, the Joint Chiefs of Staff, after extensive deliberation, issued to General MacArthur, Admiral Chester Nimitz, and Army Air Force General Henry Arnold, the top secret directive to proceed with the invasion of Kyushu. The target date was after the typhoon season.
President Truman approved the plans for the invasions July 24. Two days later, the United Nations issued the Potsdam Proclamation, which called upon Japan to surrender unconditionally or face total destruction.
Three days later, the Japanese governmental news agency broadcast to the world that Japan would ignore the proclamation and would refuse to surrender. During this same period it was learned -- via monitoring Japanese radio broadcasts -- that Japan had closed all schools and mobilized its school children, was arming its civilian population and was fortifying caves and building underground defenses.
Operation Olympic called for a four pronged assault on Kyushu. Its purpose was to seize and control the southern one-third of that island and establish naval and air bases, to tighten the naval blockade of the home islands, to destroy units of the main Japanese army and to support the later invasion of the Tokyo Plain. The preliminary invasion would began October 27 when the 40th Infantry Division would land on a series of small islands west and southwest of Kyushu. At the same time, the 158th Regimental Combat Team would invade and occupy a small island 28 miles south of Kyushu. On these islands, seaplane bases would be established and radar would be set up to provide advance air warning for the invasion fleet, to serve as fighter direction centers for the carrier-based aircraft and to provide an emergency anchorage for the invasion fleet, should things not go well on the day of the invasion.
As the invasion grew imminent, the massive firepower of the Navy – the Third and Fifth Fleets -- would approach Japan. The Third Fleet, under Admiral William "Bull" Halsey, with its big guns and naval aircraft, would provide strategic support for the operation against Honshu and Hokkaido. Halsey's fleet would be composed of battleships, heavy cruisers, destroyers, dozens of support ships and three fast carrier task groups. From these carriers, hundreds of Navy fighters, dive bombers and torpedo planes would hit targets all over the island of Honshu. The 3,000 ship Fifth Fleet, under Admiral Raymond Spruance, would carry the invasion troops.
Several days before the invasion, the battleships, heavy cruisers and destroyers would pour thousands of tons of high explosives into the target areas. They would not cease the bombardment until after the land forces had been launched.
During the early morning hours of November 1, the invasion would begin. Thousands of soldiers and Marines would pour ashore on beaches all along the eastern, southeastern, southern and western coasts of Kyushu. Waves of Helldivers, Dauntless dive bombers, Avengers, Corsairs, and Hellcats from 66 aircraft carriers would bomb, rocket and strafe enemy defenses, gun emplacements and troop concentrations along the beaches.
The Eastern Assault Force consisting of the 25th, 33rd, and 41st Infantry Divisions, would land near Miyaski, at beaches called Austin, Buick, Cadillac, Chevrolet, Chrysler, and Ford, and move inland to attempt to capture the city and its nearby airfield. The Southern Assault Force, consisting of the 1st Cavalry Division, the 43rd Division
and Americal Division would land inside Ariake Bay at beaches labeled
DeSoto, Dusenberg, Essex, Ford, and Franklin and attempt to capture
Shibushi and the city of Kanoya and its airfield.
On the western shore of Kyushu, at beaches Pontiac, Reo, Rolls Royce, Saxon, Star, Studebaker, Stutz, Winston and Zephyr, the V Amphibious Corps would land the 2nd, 3rd, and 5th Marine Divisions, sending half of its force inland to Sendai and the other half to the port city of Kagoshima.
On November 4, the Reserve Force, consisting of the 81st and 98th Infantry Divisions and the 11th Airborne Division, after feigning an attack on the island of Shikoku, would be landed -- if not needed elsewhere -- near Kaimondake, near the southernmost tip of Kagoshima Bay, at the beaches designated Locomobile, Lincoln, LaSalle, Hupmobile, Moon, Mercedes, Maxwell, Overland, Oldsmobile, Packard, and Plymouth.
Olympic was not just a plan for invasion, but for conquest and occupation as well. It was expected to take four months to achieve its objective, with the three fresh American divisions per month to be landed in support of that operation if needed. If all went well with Olympic, Coronet would be launched March 1,1946. Coronet would be twice the size of Olympic, with as many as 28 divisions landing on Honshu.
All along the coast east of Tokyo, the American 1st Army would land the 5th, 7th, 27th, 44th, 86th, and 96th Infantry Divisions, along with the 4th and 6th Marine Divisions. At Sagami Bay, just south of Tokyo, the entire 8th and 10th Armies would strike north and east to clear the long western shore of Tokyo Bay and attempt to go as far as Yokohama.
The assault troops landing south of Tokyo would be the 4th, 6th, 8th, 24th, 31st, 37th, 38th, and 8th Infantry Divisions, along with the 13th and 20th Armored Divisions.
Following the initial assault, eight more divisions - the 2nd, 28th, 35th, 91st, 95th, 97th, and 104th Infantry Divisions and the 11th Airborne Division -- would be landed. If additional troops were needed, as expected, other divisions redeployed from Europe and undergoing training in the United States would be shipped to Japan in what was hoped to be the final push.
Captured Japanese documents and post war interrogations of Japanese
military leaders disclose that information concerning the number of
Japanese planes available for the defense of the home islands was
dangerously in error. During the sea battle at Okinawa alone, Japanese
Kamikaze aircraft sank 32 Allied ships and damaged more than 400 others.
But during the summer of 1945, American top brass concluded that the
Japanese had spent their air force since American bombers and fighters
daily flew unmolested over Japan.
What the military leaders did not know was that by the end of July the Japanese had been saving all aircraft, fuel, and pilots in reserve, and had been feverishly building new planes for the decisive battle for their homeland. As part of Ketsu-Go, the name for the plan to defend Japan -- the Japanese were building 20 suicide takeoff strips in southern Kyushu with underground hangars. They also had 35 camouflaged airfields and nine seaplane bases.
On the night before the expected invasion, 50 Japanese seaplane bombers, 100 former carrier aircraft and 50 land based army planes were to be launched in a suicide attack on the fleet. The Japanese had 58 more airfields in Korea, western Honshu and Shikoku, which also were to be used for massive suicide attacks.
(con't)