Sen Toku - The Super-Weapon Which Could Have Brought Down The USA

Sen Toku - The Super-Weapon Which Could Have Brought Down The USA

During the years of World War 2, when the USA was constructing the Nuclear Bomb under the guise of the Manhattan Project, Japan was secretly constructing their own super weapon. Japan’s super weapon was known as the Sen Toku. It was the largest submarine during WW2; acting as both, a conventional submarine and an aircraft carrier. To understand why this weapon was built, and why it could have brought the USA to its knees, one should read further.

Sen Toku - The Pre-Construction



During the war in the Pacific, the Allies and japan were racing each other. Both sides were desperate, both sides wanted to win, both sides were contemplating the construction of super weapons. After Japan had lost a lot of their aircraft carriers to the USA; they were determined to construct a weapon which would fulfil the role of an aircraft carrier, but one which could also infiltrate an enemy’s base. In other words, the Japanese were planning to construct a submarine which could infiltrate and bomb American cities directly, thus crippling the USA.

Sen Toku - The Construction



While in theory the plan sounded excellent, the designers behind the Sen Toku had to overcome difficult obstacles. The first problem confronted was creating a submarine which would maintain buoyancy while holding aircraft. The workaround was to construct a submarine consisting of two tubes sitting side by side. This improved the buoyancy dramatically as the submarine was then able to hold the hangar in which the aircraft sat. While this was a primary problem, the team had yet a myriad of others to overcome.

Perhaps the second most important feat was trying to fit the aircraft themselves into the hangar. The aircraft chosen for the submarine was the Aichi M6A. The Aichi M6A was a floatplane which was able to fit in the hangar of the Sen Toku through a specific method. The team took inspiration from other western planes, and decided to apply similar methods to the Aichi M6A. Aspects such as folding wings were applied in order to make the plane fit in the hangar successfully. The Japanese took it further and made the tail fin foldable in order to limit height. Having dealt with the issue of scaling the planes, the team then had to figure out how to make them take off successfully.



The Aichi M6A’s engine required a warming up period of 20 minutes. This posed a great problem, as the planes themselves weren’t able to warm up inside the hangar, risking the lives of the pilots, and they weren’t able to warm up outside of the hangar due to a risk of enemy attack. This problem was greatly expanded considering one Sen Toku could carry 3 of the planes. As such, the Japanese turned to other solutions, warming up the oil before pumping it into the planes. This allowed the planes to immediately take off upon leaving the hangar. With all of the problems solved, Japan was hoping to get the Sen Toku into the war as quickly as possible…but they didn’t.

Sen Toku - The Race Against Time

With the death of Isoroku Yamamoto (the Sen Toku’s director), the program had suddenly came to a halt. The original plan of constructing 18 Sen Toku’s was slashed to 9, as the submarine had fallen from the pinnacle of the priority list. After years of war, and the eventual construction of numerous Sen Toku’s, their original purpose was lost. Instead of attacking American cities the conventional way, the Japanese had turned to the idea of Biological warfare. The Imperial Japanese navy wanted to use Biological weapons (borrowed from the Japanese Army) in order to bomb the USA’s west coast. Fortunately for the USA, the request was denied on the consensus that “using biological weapons would lead to a war against all of humanity.”

With that out of the way, the Imperial Japanese Navy instead turned to the idea of taking out the Panama Canal, a major Allied transport route, connecting the Pacific Ocean to the Atlantic Ocean. If the Japanese were successful in destroying the Panama Canal, the allies would be forced to travel around Cape Horn (the most southerly tip of South America). Understanding that the defenses of the Canal were too great to hit effectively, the pilots were told that the mission would be a one way trip…they were ordered to go kamikaze.

The window of opportunity closed when the USA attacked the island of Okinawa. The Japanese decided that an attack on the Panama Canal would be too little too late. As such, the mission of the Sen Toku was altered yet another time with the Japanese focused on Ulithi Atoll, a major Allied staging ground in the Pacific. With the plan set, the Sen Toku’s were sent out with the orders to take down as many US Aircraft Carriers as possible. The plan was to originally send the Sen Toku’s out to Uithi Atoll and stage kamikaze attacks. But this never played out.

From the get go, the Sen Toku mission was flawed, with one submarine having been sunken and the commander of another traveling on an unspecified route (thus missing the rendezvous with the other submarines). Just as the remaining submarines were about to attack, the USA had dropped a Nuclear Bomb. With the news coming over the radio, the Sen Toku crew members were ordered to cease fire and they did so regrettingly. Both submarines ceased the mission and made their way for Japan, but it was too late.

Sen Toku – The Conclusion

Both submarines were located by US forces. The commander of the first Sen Toku surrendered peacefully while the commander of the other took his own life after the humiliation of surrendering his Sen Toku after a tense couple of hours. The crewmen were released, and the Sen Toku’s were taken to Hawaii and studied. After gaining the top secret technology of the Sen Toku, the USA quickly destroyed any remains of them due to the fear of Russia's eagerness. The USA feared that Russia would want to analyse the submarines also.

The Sen Toku had the potential to bring the USA to its knees, but fortunately did not receive the time required to do so. If the production finished earlier than what it did, then US cities would have succumbed to the wrath of the Sen Toku. If the Japanese Army had allowed the Imperial Japanese Navy to use Biological weapons, then the war would have changed for the worst. It all came down to a race against the clock, with the victory falling to the Allies.

Thanks for reading.

Sources:

en.wikipedia.org...
en.wikipedia.org...
combinedfleet.com...

Video:

I'm sorry, but one plane could not have destroyed the Panama Canal. If it had a heavy enough bomb then it might have been able to damage one of the locks, but that's a massive ask and even then it wouldn't have brought the US to its knees - why would it? The US Pacific Fleet was just too damn large by even 1943.

Capable of carrying three two-seat Aichi M6A1 "Seiran" (Mountain Haze) float torpedo bombers,


it was not 1 plane it was three and 3 subs were completed.


for a total of 9 aircraft in the fleet...


the wikipedia article links the OP provided were quiet educational


fascinating post OP

thanks

Originally posted by AngryCymraeg
I'm sorry, but one plane could not have destroyed the Panama Canal. If it had a heavy enough bomb then it might have been able to damage one of the locks, but that's a massive ask and even then it wouldn't have brought the US to its knees - why would it? The US Pacific Fleet was just too damn large by even 1943.

Each submarine could carry 3 aircraft, all capable of slipping past US defenses and hitting them where it hurts.

Their original plan was to hit US cities with bombs (each plane could only carry one). They then turned to the idea of biological warfare (after wasting too much time) which was denied.

Afterwards, they decided to go after the Panama Canal. Yes, they seen that the defenses there were too great and opted for a kamikaze attack. After the US led offensive of Okinawa, the Japanese ditched the plan for the Panama Canal.

The weapons did have the potential to bring the USA to its knees, especially if the use of biological weapons had been approved. If they stuck to their guns and hit US cities, who knows what would have happen.

Note: The key word here is "potential."

Thanks for reading though.

reply to post by rwguessjr


No worries mate!

I did leave some information out of the OP incidentally.

I'm glad you liked it

Thanks!!!

Edit: For further information, the documentary i posted is excellent. Well worth the watch!

reply to post by daaskapital


If thousand bomber raids didn't "bring Germany to its knees" why would nine float planes cause the US to surrender? The Panama canal was susceptible to attack and was heavily defended. The goal of the enemy was to hit a lock and drain Gatun lake. This would take two years to refill. What was not known at the time was that there were special "valve" locks built that would prevent the lake from draining while any lock could be repaired. The subs were an interesting sidenote but hardly a weapon that could affect the outcome of the war.

Originally posted by pteridine
reply to post by daaskapital

 

If thousand bomber raids didn't "bring Germany to its knees" why would nine float planes cause the US to surrender? The Panama canal was susceptible to attack and was heavily defended. The goal of the enemy was to hit a lock and drain Gatun lake. This would take two years to refill. What was not known at the time was that there were special "valve" locks built that would prevent the lake from draining while any lock could be repaired. The subs were an interesting sidenote but hardly a weapon that could affect the outcome of the war.

I said it had the potential to, depending on the circumstances of course.

The original plan had nothing to do with the Panama Canal. The Japanese were originally intending to bomb major US cities including New York City, Washington DC, Los Angeles, and more. That would have been a major blow to the USA's morale. Can you imagine what would have happened if the Imperial Japanese Navy were allowed to use Biological weapons against US cities (like they requested)? That would have been totally devastating. it was all thanks to a high ranking Japanese officer that the US cities weren't attacked with Germs.

The subs could have affected the outcome of the war providing they never hit all the walls that they did. If it was produced on time, then it would have had somewhat of an effect.

All this being said, the Sen Toku did have the potential to bring down the USA, even though it wasn't on the same level as a Nuclear Weapon.

Fascinating read.
Well done.

S+F!

Origin
The original plan had nothing to do with the Panama Canal. The Japanese were originally intending to bomb major US cities including New York City, Washington DC, Los Angeles, and more. That would have been a major blow to the USA's morale. Can you imagine what would have happened if the Imperial Japanese Navy were allowed to use Biological weapons against US cities (like they requested)?

Yes. Unlimited unrestricted firebombing through 1945, and then refusing to accept the Japanese surrender after dropping two A-bombs on Tokyo, and use of the next 12 weapons to come from Los Alamos over the next year, and only then accepting surrender of the irradiated survivors in late 1946.

All this being said, the Sen Toku did have the potential to bring down the USA, even though it wasn't on the same level as a Nuclear Weapon.

Not remotely close.

Fascinating, albeit laced with hyperbole. This "super weapon" could not possibly have affected the outcome of the war. At a time when B-29s were carpet bombing Japan on a daily basis with thousands of bombs we are supposed to believe that a handful of float planes with one bomb apiece would change the outcome of the war?

By the last year of the war Japan was solidly beaten. It's Navy was decimated. The American Navy ruled the Pacific so well that the only thing the Japanese could do was stage Kamikaze raids to inflict some damage. There was really no need to drop the A-bombs; Japan would have capitulated within a few weeks.

Warfare is filled with "woulda, shoulda, coulda," but it does no one any good to pretend this "super weapon," which was no such thing and was way too little way too late, was somehow a game changer. It wasn't, and even if it had been used to its fullest capability it wouldn't have changed the outcome.

Still, an interesting and little known story so thank you for bringing it up.

I do not think it would have brought down the US but it could have certainly affected the war. If they had used it to strike important targets like bomb factories weapons manufacturing and had affected resupply efforts it could have turned the tide. The use of biological agents would have been more a terror attack and would have affected moral most certainly. It would not have been a weapon that could win the war however it could have affected it most certainly.

Attacking major cities would have been to only affect moral. It was definitely an interesting weapon but you are seriously overestimating how much damage it could deliver. You have to remember all those plans would depend on them not meeting any resistance from AA guns and The US Army air corps. The key would have been being able to hit strategic targets successfully. ( 9 Airplanes against a nation would have had a very low chance of carrying out more than one mission before counter measures had been deployed. Many places in the US during WW2 had defenses in the hands of civilians. My grandparents lived in Louisiana at that time and had an AA cannon in there yard placed by the military because they lived on the coast and they knew how to use it.

reply to post by mbkennel


Actually the difference between dropping the first bomb and the second was a conditional surrender and an unconditional surrender. Up until that point the Japanese were prepared to fight down to every last woman and child. Some of the islands the US took you will find that most of the civilians would commit suicide before surrendering. The US was unaware of the effects of radiation until much later. During the Korean war there was a push to use the A bomb and the plan was to send our troops in directly after the use which would have killed our own soldiers this was due to us not understanding the full effects of nuclear weapons.

Firstly, id like to thanks you for the thread.....
The egos of some may be a bit crushed with the news, but the Sen Takus may have actually forestalled the US and forced it to settle ................even with the atomic bomb....
But thats another story..................

Interesting thread...star and flag!

The successful deployment of these ships may have resulted in a few more Japanese victories, but it's doubtful they would have secured an axis victory overall. Even to this day, everything thus far pales in comparison to the force of nuclear weapons, which is why they have never been used again.

Originally posted by stirling
Firstly, id like to thanks you for the thread.....
The egos of some may be a bit crushed with the news, but the Sen Takus may have actually forestalled the US and forced it to settle ................even with the atomic bomb....
But thats another story..................

Haha, thanks for the reply mate

Yeah, the Japanese were so close to using Biological weapons against the USA. They were lucky that one of the Japanese commanders dismissed the request. If he were as crazy as some of the other officers (on either side) then the # would have hit the fan.

If the Sen Tokus were produced on time (which they would have been if it were not for all the walls they hit), then it definitely would have had the potential to bring down the USA.

Thanks for reading.

These submarines would be vulnerable to conventional ASW tactics. Bombing cities doesn't destroy morale see Battle of Britain and the Defense of the Reich for future reference(didn't work in Vietnam either).

Originally posted by Cosmic911
Interesting thread...star and flag!

The successful deployment of these ships may have resulted in a few more Japanese victories, but it's doubtful they would have secured an axis victory overall. Even to this day, everything thus far pales in comparison to the force of nuclear weapons, which is why they have never been used again.

Thanks.

I agree somewhat.

We don't really know how effective the Sen Tokus would have been provided they were produced on time. But as i said before, the submarines had the potential to bring down the USA (especially if they were allowed to proceed with the biological weapons). It is just fortunate that they ran into the amount of walls that they did (thus rendering their Sen Tokus ineffective for the overall span of the war).

Thanks for reading

a few planes with 1 bomb each, bombing in those days was not very accurate as far as taking out any specific targets..not any kind of real threat imo..could be more of a terror weapon if they used biological weapons, or even conventional(shock value)..no way japan was bringing the u.s. to its knees with its endless resources..that japan didnt have..interesting idea though
cool thread

Originally posted by danwild6
These submarines would be vulnerable to conventional ASW tactics. Bombing cities doesn't destroy morale see Battle of Britain and the Defense of the Reich for future reference(didn't work in Vietnam either).

The Sen Toku was the most advanced submarine of the war. It was equipped with state of the art technology which was somewhat effective against the Western powers (A lot of the technology was proved effective by the Germans). The technology was so great that the USA took the submarines, studied them, gained all the technology and then sunk them. If it wasn't for the Sen Toku, the submarines today wouldn't be as great. After all, most of the modern submarines are all influenced by the Sen Toku itself.

Britain's morale was extremely low during bombing years. They were begging the USA for help (unbeknownst to them, the USA was actually supporting both sides during that time). The USA was actually hit directly by the Japanese, and a lot of people did freak out. If the Japanese advanced with the use of the Sen Toku's (against the USA) then the morale definitely would have been damaged.

Originally posted by vonclod
a few planes with 1 bomb each, bombing in those days was not very accurate as far as taking out any specific targets..not any kind of real threat imo..could be more of a terror weapon if they used biological weapons, or even conventional(shock value)..no way japan was bringing the u.s. to its knees with its endless resources..that japan didnt have..interesting idea though
cool thread

Thanks for the reply

If the Japanese had developed all 18 of the Sen Tokus (which was originally planned) on time, with 54 planes altogether, then i think they definitely could have been proven effective.

While they may not have brought down the USA physically, they definitely would have damaged the USA's morale. Using Biological weapons would have been insane, and it is fortunate that one of the commanders viewed it that way.