USA declares war on Germany in September 1939?

They might, but they wouldn't be launching an attack on an enemy at peace. They would be attacking an enemy who had been at war for two years. And while the Pacific would likely not be at the same level defense wise as the Atlantic, it would still be much higher than IOTL.

Japans logic in attacking the US was the nation had no stomach for war & would swiftly concede Japans goals in the Pacific and Asia. A US actively at was in Europe kind of disproves the sissy theory/
 

SsgtC

Banned
Japans logic in attacking the US was the nation had no stomach for war & would swiftly concede Japans goals in the Pacific and Asia. A US actively at was in Europe kind of disproves the sissy theory/
Kinda-sorta. The Japanese high command had a remarkable talent for self delusion. They'd probably tell themselves that Anerica had no stomach for a war against them. They'd also tell themselves that the Americans would do everything in their power to avoid fighting a two front war, and the timing was perfect. All their potential enemies (with the exception of the USSR) were busy fighting a war on the other side of the world. No way would they want to get involved in Asia
 
Kinda-sorta. The Japanese high command had a remarkable talent for self delusion. They'd probably tell themselves that Anerica had no stomach for a war against them. They'd also tell themselves that the Americans would do everything in their power to avoid fighting a two front war, and the timing was perfect. All their potential enemies (with the exception of the USSR) were busy fighting a war on the other side of the world. No way would they want to get involved in Asia

It the self delusion was born out of desperation. The embargos put Japan into a very tight corner, absent those they have little incentive to attack any else.
 

SsgtC

Banned
It the self delusion was born out of desperation. The embargos put Japan into a very tight corner, absent those they have little incentive to attack any else.
Except these are the same Generals and Admirals that thought they could conquer all of China within a year...
 

Geon

Donor
The United States was strongly isolationist. Any attempt by Roosevelt to guarantee Poland's independence like UK and France did would be nixed by the isolationist U.S. Congress. An overwhelming majority of Americans did NOT want war with Germany period. You would need a Pearl Harbor like incident to galvanize public opinion for getting involved in a war in 1939. One possible way would instead of the Athena being torpedoed have German U-Boats torpedo American passenger liners mistaking them for British troop convoys. (It has to be more then one) As a result Roosevelt is able to have a cassus belli to rally the U.S. behind a war effort.

However, the problem is that the U.S. armed forces were only a shadow of what they would become later in the war. I suspect the most the U.S. could do in 1939 was to aid Britain in fighting the Battle of the Atlantic. I could easily see the USN assisting the RN in hunting down the Graf Spee and later the Bismarck. They could also help in keeping the sea lanes open earlier.

In OTL many U.S. citizens joined the RAF by simply going to Canada. Here it is likely you have American pilots fighting alongside the British and Canadian pilots in the Battle of Britain. U.S. production should be kicking in by the time of said Battle so that American fighters are now joining the British Spitfires over the skies of Britain.

Unfortunately I don't see U.S. ground forces making any major influence early in the war. Hitler still gets France, the Low Countries and Scandinavia. However I can see the North African campaign (Operation Torch) happening earlier and the Germans being pushed out much faster by say 1941.

Japan still attacks PH on 12/7 in my belief. But the U.S. is much better prepared. Possibly even having a surprise counter attack in store for the IJN.

One thought, facing UK, France, and the U.S. is it possible Hitler might postpone Barbarossa? He already would have a great deal to worry about in the West and would see his plans to starve the UK going down with his U-Boat fleet. Might he decide to avoid attacking the Russians until he's dealt with the Western Alliance?
 
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One thought, facing UK, France, and the U.S. is it possible Hitler might postpone Barbarossa? He already would have a great deal to worry about in the West and would see his plans to starve the UK going down with his U-Boat fleet. Might he decide to avoid attacking the Russians until he's dealt with the Western Alliance?

It would be interesting if Hitler did postpone his attack on the Soviet Union which means his new goal would be knocking the British out of the war. Knock the British out of the war and then the US is effectively out of the war as well. To do this he would either need to starve the British of food, or starve them of oil. That means potentially putting a lot more focus on U-boat construction, but also could mean that Hitler is willing to deploy a very large amount of troops to North Africa (way more than he did in real life) in an effort to stop the British getting oil.
 
but also could mean that Hitler is willing to deploy a very large amount of troops to North Africa (way more than he did in real life) in an effort to stop the British getting oil.
Only if Hitler and his top buffoons are ignorant of the fact that nearly all Britain’s oil is coming from across the Atlantic. US was ~60% of world production and the UKs main prewar sources were IIRC Mexico, Venezuela and the Caribbean (Trinidad etc).
 
Only if Hitler and his top buffoons are ignorant of the fact that nearly all Britain’s oil is coming from across the Atlantic. US was ~60% of world production and the UKs main prewar sources were IIRC Mexico, Venezuela and the Caribbean (Trinidad etc).

So doubling down on U-Boats?

I mean it wasn't until about 1943 until the Allies managed to create the technology and the tactics that they needed to stop the U-Boats. Imagine how deadly they would have been in 1941 if there was twice as many of them.
 

nbcman

Donor
So doubling down on U-Boats?

I mean it wasn't until about 1943 until the Allies managed to create the technology and the tactics that they needed to stop the U-Boats. Imagine how deadly they would have been in 1941 if there was twice as many of them.
If the US was in the war two years earlier the production of merchant ships and escorts would also be accelerated. Who would win in a war of ship building: the Germans or the US and Commonwealth?
 
USA declaring the war on Germany on such an early date will just make it for all the people to see how German war economy was brittle.
 
What would happen if for example the Texas was in the same area as the SS America or SS Washington. Was the Texas with escorts at the time? A uboat skipper could think it a British convoy? Sinking of a BB and a liner would be the straw that broke the camels back.
 
So doubling down on U-Boats?

I mean it wasn't until about 1943 until the Allies managed to create the technology and the tactics that they needed to stop the U-Boats. Imagine how deadly they would have been in 1941 if there was twice as many of them.
Doubling or tripling the number of uboats was the most realistic way for the UK to be defeated in our timeline, but the Nazis couldn’t or wouldn’t do it. How/why do they manage it with the US all up in their faces from day one? What’s the mechanism by which adding yet another industrial powerhouse to the allied lineup doubles the combat power of the u-boat fleet?
 
I suspect it takes a clearly US liner or cruiser (or larger warship) sunk by a U-Boat with heavy loss of life... the odd garden variety merchantmen getting blown out of the water can be written off in the fog of war, but SS America or USS New York getting sunk is quite a different matter.

Add Hitler or Gobbles gloating over it and US opinion against getting involved would shift VERY rapidly. Still, suspect that puts a start more like Nov-Dec 1939 than September...

You want a way for the US to get into the war?

The US sends a BatRon consisting of the USS New York, Arkansas and Texas on a port visit to Scapa Flow at the end of the first week or so of October 1939. Being neutral, they are well lit, anchored near the entrance to separate themselves from the British combatants and do not have torpedo nets deployed.

Enter one Gunther Prien and U 47 with lots of torpedoes.

Given the low visibility, does Mr. Prien attempt to penetrate the anchorage past three high value targets, or does he look at them, yell "HELIGE SHEISS", and then set up attacks on each ship?

My guess is that later that day, October 14th, 1939 will be known as the "Day that will live in Infamy".

Belushi TD
 

SsgtC

Banned
Doubling or tripling the number of uboats was the most realistic way for the UK to be defeated in our timeline, but the Nazis couldn’t or wouldn’t do it. How/why do they manage it with the US all up in their faces from day one? What’s the mechanism by which adding yet another industrial powerhouse to the allied lineup doubles the combat power of the u-boat fleet?
I don't think it'll double it. But strangely, having the US in the war from 39 on would actually increase the efficiency of the U-Boat fleet. In the short term, anyway. With no worries about sinking nuetral US shipping, the U-boats can go crazy. For a little while. There will be more shipping crossing the Atlantic providing more targets for one. And until the US can bring it's Industrial and combat power to bear, the "Happy Time" for the KM will be even happier.
 
I don't think it'll double it. But strangely, having the US in the war from 39 on would actually increase the efficiency of the U-Boat fleet. In the short term, anyway. With no worries about sinking nuetral US shipping, the U-boats can go crazy. For a little while. There will be more shipping crossing the Atlantic providing more targets for one. And until the US can bring it's Industrial and combat power to bear, the "Happy Time" for the KM will be even happier.
I don’t really know very much about the submarine war. But it would be interesting to know what proportion of potential kills they let go due to concerns about neutrality. If they were already at max capacity in the West Atlantic they might not gain much, if they were carefully watching their shots then a big increase would be expected.
Also not sure how many extra escorts the USN would contribute. Presumably they might be able to get those horrid old WW1 destroyers refitted a bit faster than the British managed but not sure they had enough crews to deploy everything that was rusting at anchor.
 
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