[McG]

maybe. the Siberian troops that turned the tide in '41 were only available as the USSR's spy network indicated to Stalin that the Japanese would attack the US and not the USSR.
If Moscow had fallen, who's to say what would have happened? Maybe Hitler would have tried to come to a diplomatic solution in the western front in return for being allowed to plunder the USSR?

[Jawgap]

Originally Posted by Capt'n Midnight

How much information was shared ?
Even little things like impressing upon the Japanese the importance of convoys

Despite all the publicity about enigma the Germans were just as good at breaking Allied codes and knew a lot about Allied technology.

Japan lacked widespread radar, didn't use convoys, and easily broken codes.

Radar was also used in proximity shells.

a few submarine loads / few fast ship loads of cargo
plans were shared, but too late to make a difference

the big problem was developing decent kit
far too many prototypes that failed - jets were bumped up because they could run on diesel instead of the scarce petrol
heavy bombers with engines overheating
each V1 took the resources of a fighter to produce , and there was a shortage of potatoes because of the alcohol fuel which has to have knock on effects

at one stage German shells were topped up with 20% salt, because they ran out of explosives

Japan had a few wasteful schemes, the amount of manpower wasted sewing up balloons on the off chance they'd start a forest fire in the US - because that will win the war somehow

Back to codes , on the Eastern front the Russians used the public system of loudspeakers to communicate , so very little radio traffic to eavesdrop on. In Siberia it may have been different, but if the US could break the codes then perhaps the USSR could too ?

Of all the examples of shared tech, I think I'd point to two as being of critical importance - I'm sure there are others, but I'll plump for these two....

Penicillin - the Brits discovered and developed it, shared it with the Yanks who then pioneered its mass production. The Germans knew of penicillin but couldn't produce it in the volumes the Allies could.

The cavity magnetron - again developed by the Brits and mass produced by the Americans, it made centimetric wave radar a reality which allowed for smaller objects to be detected such as submarine periscopes. It also made radar sets smaller meaning they could be incorporated into more aircraft.

A lot of German prototypes didn't fail in as much they were killed by rivals anxious to promote their own designs.

There's another point about artillery shells - a lot of war production in Germany was carried out using forced / slave labour who no doubt had an incentive to mess about if / when they could get away with it.

I saw one study that suggested between 20% and 25% of the shells fired during the Germans 1944 Winter Offensive in Alsace (the Battle of the Bulge) failed to explode on landing. No doubt some of those suffered from poor materials, but the author also suggests that workers in the factories played their part in sabotaging fuzes etc.

[Capt'n Midnight]

Originally Posted by Jawgap

Penicillin - the Brits discovered and developed it, shared it with the Yanks who then pioneered its mass production. The Germans knew of penicillin but couldn't produce it in the volumes the Allies could.

very important all right, also as a note open heart surgery was developed too,

The cavity magnetron - again developed by the Brits and mass produced by the Americans, it made centimetric wave radar a reality which allowed for smaller objects to be detected such as submarine periscopes. It also made radar sets smaller meaning they could be incorporated into more aircraft.

Two key points here.
The Germans also had the magnetron but didn't develop it because they couldn't get it on a stable frequency. Neither could the Brits, but they realised you could just retune the receivers.

[Capt'n Midnight]

http://www.historynet.com/japans-fat...d-war-ii-2.htm

The Japanese had not experienced the logistical challenges that the Western powers had addressed during World War I and later relearned. Japan's politicians, generals and admirals completely misjudged the character and the duration of the war they launched in 1941. Poor aerial logistics planning, lack of foresight, a racist contempt for their enemies, a weak, shallow, narrow industrial base and an inability to appreciate supply requirements or to learn from their failures characterized their aviation effort throughout the entire war.

[Jim S]

Some good points raised which I would agree with....Japan and Germany were too distant from each other and had little in common which would promote much by way of close co operation.
Trade yes (greatly hampered by the practical difficulties in sailing round the world and back in time of war) but in terms of military support it was one way traffic really - U Boats to Penang and German technology going east.

America would sooner or later have been drawn more than likely via a naval encounter which was fast brewing potential in the Atlantic but relationships with Japan were never more than luke warm certainly never enough to produce a joint attack on Russia , as we know she had her own agenda in SE Asia.

[Reekwind]

Originally Posted by SafeSurfer

The sheer scale of Asiatic Russia would have been daunting but Japanese troops pushed as far as Lake Baikal during their intervention in the Russian civil war

No. It's easy to advance when you are facing no opposition. When the Japanese did face the Red Army in a pitched battle in the 1930s they got absolutely spanked at Khalkhin Gol. By all accounts this laid bare the chasm between the mechanised and armoured Soviets and the backwards Japanese army

So this is really not a hypothetical: the Japanese did try to take Siberia before this military rebuff tilted the political balance in Tokyo in favour of a naval competition with the US. A counterfactual that assumes that the Soviet–Japanese Neutrality Pact was not in place in 1941 would have to explain why this Japanese policy shift did not take place