Japanese Invasion of Australia
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Riain
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I've heard about a couple of schemes, one for far North Queensland and another pinching off the "Top End" as far south as the Roper River.
They could never hold it in the long term, the USN would eventually totally dominate the seaborne supply lines. However they could hold it for a time, although for what material purpose i couldn't say, because the terrain and lack of development makes these areas difficult to approach by land for a counter offensive.
They could never hold it in the long term, the USN would eventually totally dominate the seaborne supply lines. However they could hold it for a time, although for what material purpose i couldn't say, because the terrain and lack of development makes these areas difficult to approach by land for a counter offensive.
Darwin could be taken easily enough in mid-42 if the Japanese are willing to forgo some other operation (the Indian Ocean Raid probably being the most sensible to scrap). Because of how far away it is from literally anything else (there's a road to Alice Springs, but AS is still basically nowhere), it might as well be treated as an island. The Japanese had 25k men in Timor from about March. Use them.
Brisbane... won't go well. First, Japan has to take Port Moresby. No ifs, buts or maybes, they have to. Else there will be an ungodly amount of Allied subs picking off every tanker, cargo ship, transport and anything else that sails through the Coral Sea. Moresby isn't likely to fall based on the OTL attack in May, but there's enough of a chance that it can.
Next, we've got to consider Cairns, Townsville, Cooktown and other potential bases in northern Queensland. But the Allied plan was always to retreat to the "Brisbane Line", so I'll just wave those away for now. New Caledonia, on the other side, I won't. From about April 42, NC is going to be defended by the AmeriCal division, one of the best in the US Army. Something like 25k men, all well trained, well supplied (Noumea harbour was literally overflowing with supply ships at times!), probably have fairly good air support. At the same time, the Japanese have to run EVERYTHING out of Truk or Rabaul. That's a few thousand km, close to the limit of the IJN's range (for fuel if nothing else!). It can be reached, but the IJN will only be able to hang around for a couple of days. Then it is a month round-trip to refuel. That means whatever troops the Japanese land are only going to have air cover ("support" is being generous) for about one day in every ten, which will have to come off carriers (even if the Japanese take the New Hebrides, a Zero won't be able to achieve much more than flying in, fighting for like 5 minutes, and then having to go back. And I doubt Japan even had the fuel to spare to resupply Efate repeatedly. If you scrap Midway, the Japanese have enough fuel to use about a third of the IJN near-constantly until the end of the year. Then they run out entirely.
OK, so we handwave the fall of Moresby, neutralise far north QLD and the Heer Logistics Fairy finds a way to make New Caledonia work. Now what?
Well, there's something like a quarter million Allied troops on the Brisbane line by now. Australia has enough locally grown food to feed them forever (it's not like NC or another island where everything has to be shipped in). Australia has an arms industry, so at least some of their equipment will be fine (we were building tanks at one point, so rifles won't be a problem).
Japan's problem is NOT manpower. They had something like 100k on New Britain at one point and another 100k on New Guinea (IIRC that was 1943, but the troops are still somewhere - doesn't really matter). The problem is getting that manpower to the front, and supplying it once there. At Guadalcanal, the Japanese force topped out at about 30k, and Brisbane (or NC for that matter) is a lot further than Guadalcanal from wherever these troops are being supplied from (Rabaul isn't making these supplies either). My most generous estimate is that Japan could probably run 10k troops at a time to wherever they want them to go in this theatre (Midway had 5k in the invasion force, and anyone who brings up the Philippines or DEI needs reminding that those are a lot closer to Japan than Rabaul is!).
So Japan might be able to drip-feed sets of 10k men to Australia once a month. Probably less than that in successive waves as they'll need to bring more rice, ammo &c each time (even on Guadalcanal the troops weren't getting enough, and Brisbane is going to be worse!). Even Douglas MacArthur can defeat a force 1/25th of his force's size if given a month to do so.
Even the IJA thought invading Australia was such a terrible plan that they just "nope"d out of it. When those madmen think something is impossible, you can be absolutely sure that it will never work. I didn't even bring in the US Navy, but they won't make things any easier either!
If you're interested, I did write a timeline about what I think to be a sort of "best case" for Japan in the South Pacific - link is in my sig.
- BNC
Brisbane... won't go well. First, Japan has to take Port Moresby. No ifs, buts or maybes, they have to. Else there will be an ungodly amount of Allied subs picking off every tanker, cargo ship, transport and anything else that sails through the Coral Sea. Moresby isn't likely to fall based on the OTL attack in May, but there's enough of a chance that it can.
Next, we've got to consider Cairns, Townsville, Cooktown and other potential bases in northern Queensland. But the Allied plan was always to retreat to the "Brisbane Line", so I'll just wave those away for now. New Caledonia, on the other side, I won't. From about April 42, NC is going to be defended by the AmeriCal division, one of the best in the US Army. Something like 25k men, all well trained, well supplied (Noumea harbour was literally overflowing with supply ships at times!), probably have fairly good air support. At the same time, the Japanese have to run EVERYTHING out of Truk or Rabaul. That's a few thousand km, close to the limit of the IJN's range (for fuel if nothing else!). It can be reached, but the IJN will only be able to hang around for a couple of days. Then it is a month round-trip to refuel. That means whatever troops the Japanese land are only going to have air cover ("support" is being generous) for about one day in every ten, which will have to come off carriers (even if the Japanese take the New Hebrides, a Zero won't be able to achieve much more than flying in, fighting for like 5 minutes, and then having to go back. And I doubt Japan even had the fuel to spare to resupply Efate repeatedly. If you scrap Midway, the Japanese have enough fuel to use about a third of the IJN near-constantly until the end of the year. Then they run out entirely.
OK, so we handwave the fall of Moresby, neutralise far north QLD and the Heer Logistics Fairy finds a way to make New Caledonia work. Now what?
Well, there's something like a quarter million Allied troops on the Brisbane line by now. Australia has enough locally grown food to feed them forever (it's not like NC or another island where everything has to be shipped in). Australia has an arms industry, so at least some of their equipment will be fine (we were building tanks at one point, so rifles won't be a problem).
Japan's problem is NOT manpower. They had something like 100k on New Britain at one point and another 100k on New Guinea (IIRC that was 1943, but the troops are still somewhere - doesn't really matter). The problem is getting that manpower to the front, and supplying it once there. At Guadalcanal, the Japanese force topped out at about 30k, and Brisbane (or NC for that matter) is a lot further than Guadalcanal from wherever these troops are being supplied from (Rabaul isn't making these supplies either). My most generous estimate is that Japan could probably run 10k troops at a time to wherever they want them to go in this theatre (Midway had 5k in the invasion force, and anyone who brings up the Philippines or DEI needs reminding that those are a lot closer to Japan than Rabaul is!).
So Japan might be able to drip-feed sets of 10k men to Australia once a month. Probably less than that in successive waves as they'll need to bring more rice, ammo &c each time (even on Guadalcanal the troops weren't getting enough, and Brisbane is going to be worse!). Even Douglas MacArthur can defeat a force 1/25th of his force's size if given a month to do so.
Even the IJA thought invading Australia was such a terrible plan that they just "nope"d out of it. When those madmen think something is impossible, you can be absolutely sure that it will never work. I didn't even bring in the US Navy, but they won't make things any easier either!
If you're interested, I did write a timeline about what I think to be a sort of "best case" for Japan in the South Pacific - link is in my sig.
- BNC
Well, then Darwin becomes the world's largest POW camp that is supplied by the POWs.
Want to see a near-textbook example of insanity, check out the more extreme iterations of Japanese War Aims in the Pacific in WWII.... as regards Australia, the Americas, India... makes Nazi ideas like the A-A Line and the Dreaded Sea Mammal which Cannot be Named Operation seem relatively sane in comparison 
The point of invading Darwin wouldn't be to win anything. The point of invading Darwin would be to politically force your opponent to divert resources to North Australia instead of New Guinea and the Solomons.
For example, if you look at the Aluetian Islands Campaign, less than 10,000 Japanese tied down over 100,000 American soldiers.
For example, if you look at the Aluetian Islands Campaign, less than 10,000 Japanese tied down over 100,000 American soldiers.
I like to think of Japan invading Australia as The Unmentionable Marsupial.Want to see a near-textbook example of insanity, check out the more extreme iterations of Japanese War Aims in the Pacific in WWII.... as regards Australia, the Americas, India... makes Nazi ideas like the A-A Line and the Dreaded Sea Mammal which Cannot be Named Operation seem relatively sane in comparison
Why bother? There's almost no one there and everything will be trying to kill the Japanese soldiers anyway, even the grass.
By the time the Japanese invasion is possible Australia has the following Australian military formations are active and at home:
The 6th and 7th Divisions, both AIF, home from North Africa
Remains of the 8th Division, AIF, recuperating after heavy losses in Malaya
1st Armoured, active since July 1941, achieved full OOB May 1942.
The 1st, 2nd, 3rd and 4th Divisions, Citizen Military Forces, active though with some sub-units deployed to New Guinea.
The 3rd Motorized/Cavalry (name depends on the exact date...), Citizen Military Forces, active.
The 2nd Armoured Division, Citizen Military Forces, forming
The 6th, 10th and 12th Divisions, Citizen Military Forces, forming.
Plus various other bits and pieces about the place.
So, just counting Australian troops, that's 6-9 infantry divisions depending on the exact date of the invasion; 2 armoured divisions and one motorized division.
In terms of American forces in Australia...
The 32nd Infantry Division arrived in April-May 1942. (Rerouted from Europe)
The 6th Infantry Division arrived in April 1942.
So, that's 8-12 infantry divisions, 2 armoured divisions and one motorized division available.
Japanese sealift means they're hard pressed to bring more than 3 or, if really stretching things, 4 divisions to the game.
Not only is a Japanese invasion a bad idea, Australia is of little strategic value anyway.
Read “Fremantle's Submarines: How Allied Submariners and Western Australians Helped Win the War in the Pacific”. British submarines were vital to the defense of Australia. Britain also had an entire destroyer squadron in Australia, in addition to the Australia’s, United States’s, and the Netherlands’s own navies.
The 6th and 7th Divisions, both AIF, home from North Africa
Remains of the 8th Division, AIF, recuperating after heavy losses in Malaya
1st Armoured, active since July 1941, achieved full OOB May 1942.
The 1st, 2nd, 3rd and 4th Divisions, Citizen Military Forces, active though with some sub-units deployed to New Guinea.
The 3rd Motorized/Cavalry (name depends on the exact date...), Citizen Military Forces, active.
The 2nd Armoured Division, Citizen Military Forces, forming
The 6th, 10th and 12th Divisions, Citizen Military Forces, forming.
Plus various other bits and pieces about the place.
So, just counting Australian troops, that's 6-9 infantry divisions depending on the exact date of the invasion; 2 armoured divisions and one motorized division.
In terms of American forces in Australia...
The 32nd Infantry Division arrived in April-May 1942. (Rerouted from Europe)
The 6th Infantry Division arrived in April 1942.
So, that's 8-12 infantry divisions, 2 armoured divisions and one motorized division available.
Japanese sealift means they're hard pressed to bring more than 3 or, if really stretching things, 4 divisions to the game.
Not only is a Japanese invasion a bad idea, Australia is of little strategic value anyway.
Read “Fremantle's Submarines: How Allied Submariners and Western Australians Helped Win the War in the Pacific”. British submarines were vital to the defense of Australia. Britain also had an entire destroyer squadron in Australia, in addition to the Australia’s, United States’s, and the Netherlands’s own navies.
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The "Brisbane Line" never existed as a strategy. It is a myth that has long outlived it's usefulness. The entire story was cooked up by Eddie Ward who was a Labor parliamentarian. He had an uneasy relationship with Curtin, and his claims about the "Brisbane Line" led to a royal commission which found they were unsubstantiated.
The Imperial Japanese Navy was in favour of an operation against Australia, the Imperial Japanese Army, less so. There was a joint conference in early 1942 where the idea was floated but the IJA doubted the IJN's ability to move sufficient forces or supplies to the Australian continent to make it a going concern. Apparently junior officers from both sides came to blows over the issue and it was put on the semi-permament back burner.
Australia is a huge continent with a small population concentrated in the SE Corner. While it would be relatively easy to create a lodgement in the Top End, the force would be required to cross the continent, using the meagre transportation system to capture Sydney- Canberra-Melbourne to force a decision on the Australian Government. There simply was no industry as such, in the Top End worth thinking about. To the Japanese, it would be like invading China and not having any locals worth thinking about. Australia was a bare, arid place with few population centres north of Brisbane. Any attacking force would be subjected to interdiction on the sea from USN and British navy forces. On land, the Australian Army, and in particular the AIF were far better trained and equipped than the Japanese. If they attacked and held Darwin that is all they would likely to hold.
The Imperial Japanese Navy was in favour of an operation against Australia, the Imperial Japanese Army, less so. There was a joint conference in early 1942 where the idea was floated but the IJA doubted the IJN's ability to move sufficient forces or supplies to the Australian continent to make it a going concern. Apparently junior officers from both sides came to blows over the issue and it was put on the semi-permament back burner.
Australia is a huge continent with a small population concentrated in the SE Corner. While it would be relatively easy to create a lodgement in the Top End, the force would be required to cross the continent, using the meagre transportation system to capture Sydney- Canberra-Melbourne to force a decision on the Australian Government. There simply was no industry as such, in the Top End worth thinking about. To the Japanese, it would be like invading China and not having any locals worth thinking about. Australia was a bare, arid place with few population centres north of Brisbane. Any attacking force would be subjected to interdiction on the sea from USN and British navy forces. On land, the Australian Army, and in particular the AIF were far better trained and equipped than the Japanese. If they attacked and held Darwin that is all they would likely to hold.
The Japanese have all sorts of problems even before they land.
Australia is big enough they can (in 42 at least) land a force somewhere, but all the easy places are in the middle of no-where. Taking Darwin gets you... Darwin. And then what?
The only logical attack would be down the east coast, landing in the north and driving south.
But there are MAJOR problems with that. Roughly the Australian transport structure gets worse the further north you get. So you are attacking into a defending force with far better transport and logistics, falling back on their own supply bases. This is a good way to lose, everything is stacked against you. The only decent strategy is one of manouver and outflanking (trying to grind them down simply runs you out of supplies).
But this time you aren't in the jungle, and your tanks are vulnerable to every AT weapon the enemy possesses. And their own tanks, well, aren't. And your logistics are laughable, transport minimal, and you have to transport every gallon of fuel. So the allies will pound you to death with artillery when you do attack, while your own guns have this nasty tendency to run out of shells.
This is before we ask just how can the IJN actually transport the needed supplies. They are already short of merchant shipping, and now you need them to travel a lot further (lets not talk about the allied submarines, that just brings bad thoughts). It gets worse, time is on the side of the allies here, they can build up much faster than you can. While zeros may be good, your air power is limited, and any sort of attrition works in favour of the allies, they are outbuilding your aircraft production by a silly amount. Your planes are working from forward airstrips, the allies aren't - and they have radar. You can't isolate Australia from allied resupply - it's a continent! Its possible to make it a bit more difficult, but that's all it does - and likely runs your already limited fuel reserves down just attempting it.
While a short term landing and attack is possible, its actually more self-defeating than the Unmentionable Pinniped.
Australia is big enough they can (in 42 at least) land a force somewhere, but all the easy places are in the middle of no-where. Taking Darwin gets you... Darwin. And then what?
The only logical attack would be down the east coast, landing in the north and driving south.
But there are MAJOR problems with that. Roughly the Australian transport structure gets worse the further north you get. So you are attacking into a defending force with far better transport and logistics, falling back on their own supply bases. This is a good way to lose, everything is stacked against you. The only decent strategy is one of manouver and outflanking (trying to grind them down simply runs you out of supplies).
But this time you aren't in the jungle, and your tanks are vulnerable to every AT weapon the enemy possesses. And their own tanks, well, aren't. And your logistics are laughable, transport minimal, and you have to transport every gallon of fuel. So the allies will pound you to death with artillery when you do attack, while your own guns have this nasty tendency to run out of shells.
This is before we ask just how can the IJN actually transport the needed supplies. They are already short of merchant shipping, and now you need them to travel a lot further (lets not talk about the allied submarines, that just brings bad thoughts). It gets worse, time is on the side of the allies here, they can build up much faster than you can. While zeros may be good, your air power is limited, and any sort of attrition works in favour of the allies, they are outbuilding your aircraft production by a silly amount. Your planes are working from forward airstrips, the allies aren't - and they have radar. You can't isolate Australia from allied resupply - it's a continent! Its possible to make it a bit more difficult, but that's all it does - and likely runs your already limited fuel reserves down just attempting it.
While a short term landing and attack is possible, its actually more self-defeating than the Unmentionable Pinniped.
You could ask the same thing for the Americans in the Aluetian Islands. It's politically impossible to ignore. Civilians of Australia don't have our 20/20 hindsight and would have demanded action
This is the crux of it, I think. Obviously Japan is never going to be able to actually invade and hold Australia. A force holding Darwin, though? It could work and would give the rest of the Pacific forces a slight breather since this is going to cause mass panic especially among Australians for a bit, even if everyone eventually calms down and realizes how pointless it is to liberate Darwin. It's not going to win them the war, but nothing is.
The Allies have way more forces to divert then the Japanese do. Schemes like this hurt the side with less troops and material by diffusing their already limited resources over half the globe..
That's not true at all.
- Japan having 10,000 troops in Alaska kept America having over 100,000 troops troops there. According to your argument, Japan should have sent those 10,000 troops to Guadalcanal. But that would also mean that the US could send 100,000 extra troops to Guadalcanal as well which means Japan loses there more quickly.
- If you are Japan, you want to have numerical equality on fronts/battles that actually matter. Occupying a irrelevant island like Attu kept the US from deploying troops and utilizing it's numerical superiority to places where it matters, which gave Japan a better chance of winning in Southeast Asia. Another example would be the Phillipines in 1944. By occupying a politically important, but strategically irrelevant territory, Macarthur and the US army were forced to fight to retake the Phillipines, which prevents them from being utilized in the Central Pacific Offensives (Which is the only front in the Pacific that truly mattered in the late stages of the war).
- As long as Australia deploys more men to the Darwin campaign than Japan does (Which they would as I have explained in previous posts), that means the Australians can't deploy their troops elsewhere in as large numbers as they did in otl. This means that a overland campaign in New Guinea and the occupation of Port Moresby without naval support could actually succeed, as could other otl campaigns where Japan was barely defeated by Australian forces.
- Also the idea that Japan doesn't have the manpower for this is inaccurate. As someone mentioned up thread, 25,000 Japanese forces sat in Timor during this time. Also, as Ichi-Go shows, Japan has the manpower even in the late stages of the war for offensive operations.
Honestly one really interesting affect of this POD is that it would increase the tension between the IJA and IJN even further. The Army really didn't want to involve themselves in another endless money and manpower sink.
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