Operation Olympic – was it feasible?

ivanotter

All,

Reading the book “the Pacific War Companion” Richard B. Frank has a section on ‘Ending the Pacific War” it seems to be a good question to ask.

These are pointers from the book:

Based on the book, it claims that radio intercepts (and decoding I presume) revealed that Japanese forces were building up on Kyushu to the tune of 14 field divisions, CINCPAC estimated 10,290 aircraft as of August 13.

It was very different from what Marshall briefed Truman about on 18 June. That estimate was some 350,000 Japanese troops 8-10 divisions and only some 2,500-3,000 aircraft.

Willoughby declared that Japanese strength was growing to the point of a 1:1 ratio, which is not the recipe for victory.

On August 7, Marshall asked MacArthur for his personal view. He did not believe the intelligence estimates and recommended to go ahead.

Admiral King intervened. August 9, King ordered Nimitz to make his views known in Washington and to MacArthur (Nimitz had at that stage voted against Olympic. Nimitz told them that a Japanese surrender might be at hand.

In sum, radio intelligence evidence made it virtually certain tat Olympic would never have gone forward, not because it was unnecessary, but because it was unthinkable.

So much for quoting the book !

Wiki says – on the nuclear aspect:

“Colonel Lyle E. Seeman reported that at least seven Fat Man-type plutonium implosion bombs would be available by X-Day,”

“Ken Nichols, the District Engineer of the Manhattan Engineer District, wrote that at the beginning of August 1945, "[p]lanning for the invasion of the main Japanese home islands had reached its final stages, and if the landings actually took place, we might supply about fifteen atomic bombs to support the troops”

So far so good.

Here is the theory:

IF an invasion was to take place as planned (March 1946), would it have been a disaster? Could Ketsu Go have worked after all?

IF mining of the coastal and inland waterways had been stepped up together with bombing the entire railway network, how much would the wholesale starvation have meant for Ketsu Go?

IF a total of 15 nuclear bombs had been used for the invasion, would it have made any difference really?

In essence: Is Mr. Frank correct in saying that (at least) Olympic would never have been launched?
 

Scott Washburn

If the Japanese had not surrendered then Olympic was going to take place in November 1945. Large military operations build up a momentum that is almost impossible to stop. It's not like they could just park the invasion fleets and wait around for a while to see what might happen on the diplomatic front.

And starvation was not going to wreck the Japanese defenses (as it DID to the Americans and Filipinos on Bataan in 1942). As food got short, the Japanese warlords would have made sure that the military and the factory workers got fed. If old people and women and children starved, they were just serving the Emperor.
 

BobTheBarbarian

If launched as planned Olympic would have been a catastrophe. By November US forces would have been outnumbered about 2:1 on the ground and 4:1 in aircraft (probably closer to 8:1 if fighters only are counted - after all, dive bombers can't shoot down kamikazes). Furthermore, a Typhoon ("Louise") would have delayed invasion preparations by 30 to 45 days, giving the defenders a material and psychological boost ahead of the battle.
 

merlin

One can only hope that that atomic weapons wouldn't have been used in a tactical way!! US soldiers would've been dying for decades to come as a result.
One other problem, if the invasion did go ahead - how was it to end, the Military would then be in charge, no way for a civilian government with the Emperor's assistance can surrender. So what Japanese General would agree to surrender?? Japan would go back to the Stone Age!!
 

ivanotter

The use of nuclear bombs as tactical weapons would have been problematic. US scientists advised that troops should only go in after 48 hours.

That would leave a vacuum as far as I can see?

Would Japanese troops be rushed to the areas? Probably not adhering to the 48 hours.

Wiki does not state how the up to 15 bombs could be used. One assumption is that they would be dropped on the beaches and the immediate fortifications, allowing an easier entry across the beaches. HOWEVER, how would that work with the 48 hours?

Airfields could be an option, but surely not on Kyushu as US would like to use those airfields later.

Does anybody know the strategy of using tactical nuclear bombs at this early stage?
 

BobTheBarbarian

ivanotter said:
The use of nuclear bombs as tactical weapons would have been problematic. US scientists advised that troops should only go in after 48 hours.

That would leave a vacuum as far as I can see?

Would Japanese troops be rushed to the areas? Probably not adhering to the 48 hours.

Wiki does not state how the up to 15 bombs could be used. One assumption is that they would be dropped on the beaches and the immediate fortifications, allowing an easier entry across the beaches. HOWEVER, how would that work with the 48 hours?

Airfields could be an option, but surely not on Kyushu as US would like to use those airfields later.

Does anybody know the strategy of using tactical nuclear bombs at this early stage?
Click to expand...

According to General Marshall - three on the beaches, three on the intermediate defenses, and a final three on the expected counteroffensive coming south from Mt. Kirishima.
 

ivanotter

Thanks Bob,

It raises the good question. If that had been done, then what? If any US troops are only allowed in after 48 hours, I should suspect that Japanese troops are rushing to the area?

Would they then be overcome by radiation sickness? When US troops arrive, what will they then do? Fearing the same fate?

The usage becomes a bit 'iffy'.
 

Michele

Assuming no changes to the US plans, and no great changes to the Japanese deployments (which would be unlikely; the Japanese had largely done what they planned to), the US 1st and 11th Corps would have a 3:1 superiority and the Marines Corps a 1.5:1 superiority on X day. Counting the Japanese divisions that were deployed in the area that Olympic was planned to occupy, the overall force ratio was 2:1 for the attackers.

Naturally, if we count the divisions in all of Kyushu, the ratio was 1:1. But the Allied plan never was to occupy all of Kyushu. The program was to reach a stop line that would place the Southern bays out of artillery range, and stop there. The seven Japanese divisions in the North of the island (and any other reinforcement from further afield, assuming it could even access Kyushu) would not be attacked by the Allies where they were. They would have to leave the safety of their bunkers and underground shelters, and move in the open in order to counterattack.

And they would be slaughtered from the air, as well as from naval artillery. The German reinforcements for Normandy experienced very high attrition rates while moving forward, both due to the shambles that the French rail network was and due to continuous air attacks. But at least they could move with relative impunity at night (still having problems with the cratered roads etc.). In the case of Olympic, night raids would be hitting the roads.
What little would be left of these reinforcements would presumably have to counterattack Allied defensive positions. We can imagine how successful these charges could be.

The Japanese had a moving trust that the kamikazes would sink astounding amounts of transport ships, based on previous experience and generous assessments of their effectiveness. The problems with this:
- The bases from where the kamikazes were taking off were largely not attacked; in this scenario, there would not be a non-cratered runway anywhere.
- The pilots of the initial kamikaze operations included a reasonable proportion of previously trained servicemen. By late 1945, most of the kamikazes would be newbies with 20 to 50 hours of flight. The Japanese simply lacked the fuel to train them.
- Old aircraft were old, with all that that entails. Newly delivered aircraft, OTOH, according to Japanese estimates, had a 70% chance of malfunctions or complete mechanical breakdowns due to non-existent quality controls. Again, they lacked fuel for tests.
 
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