Their reliance on the theory that battleships would win the war with America. Their strategy of provoking a large battleship conflict in blue water led to the failures on every level from the decicison to attack battleship row in Pearl Harbor to their innability to adequately equip their infantry with decent weapons for defending islands.

If they had the forsight to see the importance of the aircraft carrier and the island hopping strategy the Americans would later adopt both the Japanese technological investments and strategy would have been completely different.

Here's a hypothetical.........

''What if'' Japan, as part of the tripartite Axis, didn't make the mistake of attacking Pearl Harbour, and instead just attacked the European colonial possessions while doing their best to placate the U.S., would America declare war?

Yamamoto feared that Japan did not have the resources to win a war with the U.S., so reluctantly advocated a surprise attack on the US Pacific Fleet at Pearl harbour and then overrun South East Asia, fortify island bases and bleed the Americans so much that they would eventually think it wasn't worth the effort.

But by making that undeclared attack on PH, it stirred up a hornets nest, and made sure the Americans would never stop until Japan was crushed.

The attack against Hawaii was in fact the worst possible thing that Japan could have done. U.S. plans were, barring any direct attack against the Philippines or U.S. possessions, was a strictly defensive posture against Japan. The short term goal of the Japanese was to obtain the oil supplies, rubber, and other strategic materials from the East Indian possessions of the Netherlands, Great Britain, and France. Given the isolationest temperament of the U. S. Congress at the time, is it questionable, even doubtful, that the United States would have responded directly to the seizure of those foreign Colonial possessions?

When the Japanese moved into French Indo China the U.S. placed the oil embargo but didn't threaten war.

Yeah, but that's just as theoretical Ashes.

I think those that try to boil down wars to one event or one day are making the huge mistake of oversimplifying the extremely complex and extremely powerful force that is warfare.

Yep, it's just a hypothetical Whispering Death, like many on these boards, but it could have been a possible scenario, so what do you think, would the U.S. declare war in those circumstances or not?
And by the way, a heck of a lot depends on your answer.

I think it was inevitable that the two countries had to go to war. Their mistake was thinking they would beat the American navy just like they beat the Russians when warfare had changed from battleships to aircraft carriers.

So, under those circumstances you think Roosevelt would some how get congress to declare war, or did he need the congress to back him?

American opinion was against war in Europe, but the Pacific may have been a different kettle of fish.

On the carriers vs battleships, Japan was one of the leaders in pioneering carriers, the Pearl Harbour debacle was carried out by Japanese carriers, and Midway was a close run thing, but Japan had no chance of matching Americas massive volume of production, over 100 carriers of all types built.

Ah, but there you are mistaken. One wing of the Japanese navy understood carrier conflict but it wasn't realized in full untill it was too late. Note the prime aim of the Pear Harbor attacks, battleship row. Not carriers, not aircraft, not fuel.

By the time they realized the true value of the carrier it was Midway and the Americans where on the same page. In fact, you can say that it was Pearl Harbor and the quick annihilation of the battleship fleet that convinced the Americans even before the Japanese that aircraft where the key to victory, not Battleships.

The Japanese, steeped in tradition, where still planning on the same strategic level that defeated the russians. Quickly dispatch of the enemy's eastern fleet to draw the 2nd fleet (North Sea for Russia, Atlantic fleet for America) into a climactic battleship duel that would decide the war. That's why they invested so much into massive battleships like the Yamato and so little into fighter pilots who where dispatched by the hundreds in the Marianas.

Originally Posted by Whispering Death

Ah, but there you are mistaken. One wing of the Japanese navy understood carrier conflict but it wasn't realized in full untill it was too late. Note the prime aim of the Pear Harbor attacks, battleship row. Not carriers, not aircraft, not fuel.

actually, the primary targets for that attack were indeed the three aircraft carriers of the Pacific Fleet....however, on that day, those three aircraft carriers were out training, so they were lucky...but the rest of the fleet wasn't so lucky

That has some reality but a lot of myth to it. True the aircraft carriers where primary targets, but it is no coincidence that the battleships where all lined up durring the attack while the carriers where out at sea. They made sure to attack when the battleships where most vulnerable because their assumption was that they where the biggest threat. It isn't a coincidence that the japanese attacked on the exact day that the battleships where most vulnerable, at the exact time when the battleships where most vulnerable.

Did any minisubs, spys, or scout planes ever try to radio back, "CALL OFF THE ATTACK, ALL THAT ARE HERE ARE BATTLESHIPS NOT CARRIERS!" Did Yamamoto ever say, "we have to call of the 2nd wave of bombers because there are no carriers there! We must save our armarments until we find them, quickly send out all avaliable search planes to find those carriers!"

Even in Midway they had only kinda' gotten the whole carrier idea. Remember that the carrier task force was sent out ahead of the MAIN invasion force comprised of their most powerfull battleships.

By the Marianas campaign the Japanese navy had fully realized the new method of war but by then the turkey shoot proved that they had incorrectly apropriated funds to battleships instead of aircraft. The cornerstone of their vision of the grand climactic battleship duel, the Yamato, was blown to pieces by American airpower on a suicide mission to Iwo Jima and sank with all hands.

Well, That is indeed one of the HUGE mistakes of the Japanese Army!