Why would Germany declare war on the U.S?

[elvis]

...and what would have happened if they hadn't? I realize Germany signed a "non-aggression pact" with Japan, but Hitler really assured the destruction of Germany by declaring war on the U.S.


If he hadn't signed the pact, or had he renegged on it, would the US have declared war on Germany or focussed solely on Japan?

How much quicker would the war in the Pacific have ended had the US had 100 percent of its forces dedicated to it, rather than only 35?

 

[RetiredGySgt]

...and what would have happened if they hadn't? I realize Germany signed a "non-aggression pact" with Japan, but Hitler really assured the destruction of Germany by declaring war on the U.S.


If he hadn't signed the pact, or had he renegged on it, would the US have declared war on Germany or focussed solely on Japan?

How much quicker would the war in the Pacific have ended had the US had 100 percent of its forces dedicated to it, rather than only 35?

He thought Japan would live up to their promise to attack the Soviets. It was a HUGE mistake on his part.

We would have eventually declared war on Germany but there were powerful forces against the idea. However with a full war in the Pacific Roosevelt would have been able to provide more material to England. We had basically really been at war with Germany since the Summer. We had taken over half the Atlantic convoy protection and were shipping tons of material to England.

I do not see a much quicker win in the pacific cause of the fact most ship building was already going to that theater and they had more than enough air craft. Until the Carriers were available we really couldn't do much more. With more troops maybe a few months quicker once we had the naval assets.

Even so until the Nukes Japan was not going to surrender and even with them almost did not.

And since we would have gotten at war with Germany before the Carriers were ever ready, I don't see a big influx of troops to the pacific.

 

[elvis]

He thought Japan would live up to their promise to attack the Soviets. It was a HUGE mistake on his part.

We would have eventually declared war on Germany but there were powerful forces against the idea. However with a full war in the Pacific Roosevelt would have been able to provide more material to England. We had basically really been at war with Germany since the Summer. We had taken over half the Atlantic convoy protection and were shipping tons of material to England.

I do not see a much quicker win in the pacific cause of the fact most ship building was already going to that theater and they had more than enough air craft. Until the Carriers were available we really couldn't do much more. With more troops maybe a few months quicker once we had the naval assets.

Even so until the Nukes Japan was not going to surrender and even with them almost did not.

And since we would have gotten at war with Germany before the Carriers were ever ready, I don't see a big influx of troops to the pacific.

I agree Japan was not going to surrender. Is it true it was the Soviet declaration of war on Japan that convinced them to surrender?

 

[RetiredGySgt]

I agree Japan was not going to surrender. Is it true it was the Soviet declaration of war on Japan that convinced them to surrender?

No, the atomic bomb brought the emperor to his senses but he still wavered. The second attack sealed the deal. Yet even after he made his decision the Army tried to stop him, the night before the broadcast an Army Major and his men invaded the Palace and tried to find the recording to prevent its broadcast , they called for the Military to rise up and prevent the surrender. They were pawns of the Army members of the Government.

The Atomic Bomb and the End of World War II: A Collection of Primary Sources

 

[mightypeon]

There were several reasons:
1: Germany was more or less at war with the US before the declaration anyway.
2: Hitler assumed that the US would focus on Japan, since they after all suprise attacked them.
3: Hitler counted on Japanese support against Russia

Considering the Japanese capitulation:
I would say the nukes had a larger impact. While the Soviet union invaded Manchuoku in overwhelming force and obliberated the Japanese Kwantung army in a matter of 2 weeks, the communications from the Occupied China to Tokio were likely too damaged for the Japanese high command to have a clear picture of what was going on. Japans army also had a tendency to supress bad news, I would picture that the Emperor knew how bad the situation in Hiroshima was, but did not knew about the scope of the total defeat in manchuoku.
I always saw the nukes as a move to ensure that Japan capitulates to the "right" nation.

Without the nukes, the fight would have continued a bit longer, considering that the Russian had plans to launch amphibious invasions of Hokkaido and northern Japan, we might have gotten a "split nation/protectorate" result like in Germany or Korea.