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I would like to know what American military planners in WWII really thought about the possibility of a Japanese invasion of the West Coast Did they seriously think there was a real threat of this happening? If so, why?

I, for one, can't imagine anyone taking the idea seriously, considering the difficulties involved. Even assuming they could have gotten an invasion force to the West Coast and landed them without incident, their troubles would have been just beginning.

To supply their Army and Navy would have been nie on impossible considering they would have had to trace a tenuous supply line thousands of miles long across the Pacific, which would have been subject to interdiction by every submarine and surface craft available to the US and Canada on the West Coast or at the Hawaiian Islands. Likewise for the air power of the US Navy and Air Forces.

Any invasion fleet off the American coast would have been ravaged by unending attacks from land based aircraft and would have been unable to easily replace it's losses, especially in carriers and carrier based aircraft, while the Americans could send planes straight from the factory into the battle (a la Stalingrad). Even if the Japanese had managed to capture the Hawaiian Islands, while easing their supply problems, this would not have had much effect on the decisive battles being fought further east.

As for the invading armies, what would their objectives have been? Conquest? Hardly. How do you conquer a country the size of the USA? Perhaps a large scale raid designed to destroy American factories and port facilities? But no matter how successful these limited objectives might have been, the cost would have been the ultimate elimination of the invasion force which would have withered and died on the vine from lack of supply and casualties.

A Japanese attack on the United States would have been a suicidal Banzai charge of monumental proportions. It would have been the turning point in the war, but certainly not in the way the invader envisioned.

So, back to my original question. How did the military planners view the likelihood of attack? I'm willing to bet that they had contingency plans made up, maybe even years before the war with Japan started. But armies draw up contingency plans for the most unlikely of circumstances. Heck, even the Canadian Army in the 30's, for training purposes, drew up a war plan for attacking the USA (success for this plan depended on surprise - therefore we would attack at night!).

I'm curious to know what thoughts others have on this subject. Cheers.

A raid to destory the gates/locks of The Panama canal would have prevented us from moving ships from the east coast to the West Coast. The lake that fills the locks would have drained down into the oceans. We would have been required to replace the gates. That I am sure we would have done in record time. But it would have take a very long time to refill the lake to be able to move ships again through the Panama Canal. Also, being a native of California just taking and holding for a little while the ports of San Diego, L.A./Long Beach, San Francisco/Oakland, Portland, and Seattle would reduce our ship yard capacity to build ships and move men and material into the Pacific Theater. Image all that stuff having to go down around the tip of South Amercia and on fewer ships. The Japanese would just have put all their long range subs down at tip of South Amercia and maybe a surface task forced maybe based in Chilie to attack those convoys. The Japanses needed only to send ammo/uniforms for troops to West Coast. There is and was plenty of food from California farms rice farms in Sacramentro Delta produces a large portion of Rice for Asia to this day, and Oil fields in L.A. area for their planes, trucks and ships. Until we took those ports back we could do little beyond our shores to hurt Japan giving them time. Calif. population was much smaller then and even then L.A. basin was still mostly farmland then. We had few divisions to defend the country at the start with and had just started massive training of pilots and troops and naval building program.
Any aircraft manufacturing in Southern california would be lost as would Boeing building B-17's and B-29s in Seattle plants and warships and Liberty ships being built in West Coast Yards at that time would not be finished or ours to use until we took back those ports.
I think Japan would have held out for another 2-3 years and maybe even delayed us helping in Europe theater due to fewer ships in pipeline giving Germany a year or 2 more. So ending up with most if not Western Europe in including France under Soviet control. Our Industrial capacity would have still eventfully overwhlemed Japan in the end.

You left out the 1 thing that would surely prevent a large scale invasion of any success and that is Americans, armed with guns and lots of them..
I don't think even the US military at that time would have been able to control the swarms of gung ho farm boys and their cousins making a mass exodus across the country.
Hell.. half of Chicago owned Thompson SMGs..
My grandfather left us with a 30 gun collection when he passed on... I'm still using his shotgun for hunting to this day.

The Attack on Pearl was enough to incite an entire country, that just a few years prior, wanted to let the rest of the world deal with it's own problems.
The patriotism of that generation will never be matched in terms of total commitment and determination in following thru to the finish.

RedDevil Wrote:Hell.. half of Chicago owned Thompson SMGs..
My grandfather left us with a 30 gun collection when he passed on... I'm still using his shotgun for hunting to this day.

Who was your grandfather,Randy?Al Capone? :smoke:

raz_atoth Wrote:Who was your grandfather,Randy?

Yosemite Sam

RedDevil Wrote:The patriotism of that generation will never be matched in terms of total commitment and determination in following thru to the finish.

Well said RedDevil! btw I think the same goes to most of the nations involved in WWII. It is much different today, the youth tends to think only about themselves :rolleyes:

Sorry Red Devil, I didn't mean to exclude the efforts of American land forces, both regular and irregular. I sort of assumed the army would be forefront in the land defense. In fact, while I was writing that post I did have the movie "Red Dawn" in mind. Wolverines!

Guys,

I'm not sure any large scale invasion of the US by Japan was feasible... Read "War Plan Orange" to see what the American planners were thinking in the 1930's. They were focused on battling it out in the Western Pacific with the Japanese. Pre-war Japanese planning as well as war time strategy was always to seek the big naval victory to force diplomatic negotiations, ala the Russo-Japanese war of 1905.

Japan was fighting a limited war, or so they thought. They had plans to seize terrain, dig-in, hold terrain to wear out the expected counterattack, and settle the war with a diplomatic solution that recognized their premiere status in the Pacific. Their military leadership, especially Yamamoto, had no illusions about the ability of Japan to go toe to toe with the full might of the US for any length of time.

After Pearl Harbor, there was widespread hysteria in the States. I'm pretty sure that the American military did an assessment of the Japanese invading the West Coast. One of the things that came out of those assessments was the internment of Japanese Americans... I think the military leaders finally settled on fending off naval air raids and submarines as the most probable enemy course of action...

I don't think the Japanese had the logistical underpinning to take on such a massive endeavor... It would have been a little more difficult than moving troops and ammunition...

In my very rough estimation, it would have required over a million troops, probably multiple millions... and the Japanese did not have that kind of Army sitting about or the transports to get them there... They were locked in combat in China... In fact, the bulk of the Japanese Army was always in China... They were looking over their shoulders at the Russians... looking to the South at the British... and were very concerned about their economic lifeline within Asia after they seized all the territory...

First requirement for invasion of the US, would have been the capture of Hawaii. Ships don't sail thousands of miles with no place to refuel and rearm after the fighting is done. Amphibious landings in 1941/42 were not near the 44/45 capability... I believe the capture and control of Hawaii is the minimum requirement to even contemplate the invasion of the continental US West Coast.

An invasion of Hawaii would have been feasible in the wake of the Pearl Harbor strike, but the Japanese had not prepared to follow up such a wildly favorable outcome and were very busy taking apart the Dutch and British possessions to the South.

Japan was focused on knocking the European powers out of Asia and making a diplomatic settlement with the Americans... I don't think they were seriously contemplating invading America to force a settlement...

Their strategy was to come out fast and furious to knock everybody down and out, then go rope-a-dope to wear out the expected counterattack...

Unfortunately for the Japanese, the diplomatic fiasco in delivering the declaration of war was out of synch with the Pearl Harbor strikes... In Yamamoto's words... "I fear we have awakened a sleeping giant and filled it with a terrible resolve..."

Jim von Krieg
Rear CP Killeen

Well I think if they ever did take an invasion seriously they would definintely need to hold Hawaii. But the main and most direct route would be to continue island hopping up the Aleutians, Kodiak, and then head out towards Sitka, etc... Great circle route right?

Any invasion or even raid attempt on the US mainland would have been at the expense of just about all other action. And I don't think the Japanese had the supplies, particularly oil, to make the attack possible. At the start of the war, they were stockpiled with oil reserves to a degree, but they desperately needed to capture a source of oil to keep going, hence the invasion of the DEI, et al.

Going to the US would have consumed oil, and a lot of it, not produced oil. Even any oil production located on the West Coast, assuming they could capture it intact and get it on-line quickly, would not have produced a net positive oil flow to the Home Islands.

There just wasn't really anything on the West Coast they needed. And certainly nothing to justify abandoning all their other objectives.