Many people have wondered what would have happened in World War, 2 if Hitler had not declared war on the United States after Pearl Harbor.  Congress had reason to declare a state of war existed between the United States and the Empire of Japan, but no such reason until Hitler's declaration.  American men enlisted to fight the Japs, not the Hun, so I wonder whether our government would have embroiled the country in a two front war, as unprepared as we were, had it not been for Hitler's faux pas?

Could the British turn back Rommel with nothing but material support from the US?  Would the Soviets have been able to turn back Operation Barbarosa, or would Stalin have sued for peace?

Would the War in the Pacific have ended earlier, but after a terrible bloodbath invasion of the Japanese homeland?

I think Big Daddy Roosevelt would have found a casus belli for us.  Recall that the destroyer Reuben James was sunk by Otto Kretschmer but that wasn't enough outrage to silence the peaceniks.  Roosevelt had one of our oldest battleships, Texas, go into war waters where U-boats were known to be active.  One U-boat actually stalked the Texas and was in position to fire a spread of torpedoes.  All she wanted was the oh-kee-doh-kee from Berlin.  Berlin said, "Nein!"  The U-boat backpeddled water.  Sooner or later, something would have happened that would have invovled the US.

Quoted:

Could the British turn back Rommel with nothing but material support from the US?

I think the British would have eventually won in North Africa.  The biggest problem for the Germans in North Africa was that available resources were being syphoned off for the war against the Soviets.

Would the Soviets have been able to turn back Operation Barbarosa, or would Stalin have sued for peace?

I don't think Stalin would have ever sued for peace and I doubt Hitler would have accepted it.  The ideologies hated each other too much.

Would the War in the Pacific have ended earlier, but after a terrible bloodbath invasion of the Japanese homeland?

Assuming we were directing all our resources against the war in Japan, I would probably say the war would have ended earlier.   GIven the changes in the dynamics of our forces I would not venture a guess if Japan would have fought so stubbornly or not.

A senario that would make your question much more interesting is this:

Suppose the German Luftwaffe was successful in the Battle of Britian to the extent that they owned the skies.  Hitler never really wanted to invade England.  He was hoping for England to remain neutral via a peace settlement and got kind of pissed when he was told to piss off.  His true enemy was always the Russians.  Also, The British military did studies after the war which played out that even if the Germans had control of the skies and were able to mine the channel that operation Sea Lion would still have failed.  It was played out that the English Navy was too powerful and would have eventually cut off supplies and isolated German troops on the English beachhead.

But, given the failures of the British forces in France and their retreat at Dunkirk, the loss of the battle of Britian may have been enough to have Churchill removed and replaced by Foreign Secretary Lord Halifax, who was a strong proponent of peace negotiations with the Germans.  

So given a peace settlement with England, Hitler who was not thrilled about attacking American merchant ships anyway in order to avoid another Lusitania type incident would probably have not declared war on the U.S.

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Britain's Finest Hour?    Hitler's Blunder?

Quoted: A senario that would make your question much more interesting is this: Suppose the German Luftwaffe was successful in the Battle of Britian to the extent that they owned the skies.

Hehehe!  

Actually, I had that in mind for another topic, "What was the greatest blunder of WW2?"  The Nazis were headed for victory with Operation Eagle.  They were on the verge of annhilating the RAF, which would have left the Royal Navy without aircover.  One need only read about Taskforce Z to see what happened to the mightiest British war vessels when operating without air cover.

^^^^
Task Force Z - The HMS Prince of Wales and Repulse were sunk by Japanese aircraft on Dec 10, 1940
See, The Destruction of Taskforce Z

What saved the Brits was a blunder by a Luftwaffe pilot, who while "lost" jettisoned his bombs on London on August 23, 1940.  There was a retaliatory RAF bombing raid over Berlin two days later, which angered and embarrassed Hitler so much that he decided to level British cities.  On September 7, 1940, the Nazis changed their strategy from bombing airfields and factories to bombing civilian population centers.  The German pilot's blunder may have changed the course of WW2!  Still, there were many, many other blunders by both sides.  Hitler's gambles at the Battle of Kursk and the Battle of the Bulge come to mind, as does his refusal to evacuate his North Afrika Corps as requested by Rommel, or to let his army withdraw from Stalingrad.  Japan's blunders at the Battle of Midway, not to mention attacking Pearl Harbor without first declaring War were also pivotal.  What would have happened if the Japs chose the USSR to fight, instead of the US?.  The allies made their share of mistakes, too, but thankfully survived them.

If the japs and germans left us alone we would be in a very different world
Fortunately Hitler was a idiot and Goring was too wasted most of the time

I think we would have declared war on Germany anyway.

We would have still kicked his ass.

I think FDR would have prosecuted war with Germany regardless. I think he would ignore any objections from congress. Now, who controlled congress? My guess is New Deal Democrats.

Hitler fully intended to attack the US, however not yet, he had a time line, he wanted to subdue Europe first then attack the, US....

After the Japanese attack on Pearl Harbor Hitler flew into a rage, he was furious at the Japanese, he knew there actions would bring us into the war, so at first he refused to asist the Japanese, as far as he was concered we were Japans problem not his, but they threatened that if he didn't declare war theyed call off there alience, and Hitler required the Japanese aswell, so he was forced to declare war on us....

But in this scenario we will speculate that Hitler told Tojo what to do with himself....  With the allience with Germany cut off there would be no further, trade, communication, or cooperation between Germany, and Japan, Japan would be cut off, and with out Europe distracting us we would have focussed all our energy on Japan, however Churchill was counting on getting us into the war, and was thinking of ways to do it, Pearl Harbor was an answer to his wishes, and he managed to get us to foccuss on Europe first, but in this scenario were to occupied with Japan, so other than lend lease and the other little subtle things we were doing it would be up to Britain and Russia, though I'm sure at some point we would have been drawn in, but in this scenario, I'm going on the assumption that we do not....  The Pacific War likely would have been waged in much the same way though with more resources involved it probably would have been much simpler, with the greater manpower, and figures like Eisenhower involved we probably would have fought the Japanese off at Wake, and possibly even prevented them from takeing the Philippines, or from launching the Illushian campaighn, the Manhatten project would still be employed however the bomb would not have been ready by the time we reached Japan, which probably would have been atleast a year or 2 sooner, the battle or Japan would have been one of the fiercest in History possibly even bigger than Normandy, every man women, and Child was prepared to fight, some were litterly armed with pikes, we saw the fanatisism of the Japanese in earlier battles, the battle for Japan would have been epic....  Meanwhile in Europe Britain is vertually isolated they don't have the troops to invade mainland Europe on there own, so there entire army would be defensive, atlest in terms of the home island, atleast in the near term, without convoy cover the supply flow into Britain would be a trickle if not completely cut off, the RAF was good but without more materials comeing in, and with a finite number of pilots, they could only have battled the Germans for so long, as far as North Africa, it would be extremely tricky to resupply the troops, and they were operateing without American backup, the fighting would have been prolonged, but the British troops in North Africa would eventually been forced to Surrender, Britains air cover would eventually be depleted, and the population starved out, and forced to sue for peace, whethor or not Germany actually invaded Britain would have depended on the situation with the Russians....  As for the Russians they were very frustrated that there allies were't assisting them, and they were doing all the fighting, and infact threatened to sue for peace unless the Western Allies acted soon, but this time there only allie would be Britain, and they would be able to tell that they weren't going to be able to do anything, the Russians probably would have sued for Peace, but since, Hitler wsn't desracted by a second front he would not have accepted, the war would have been vitiouse, German troops would have taken Moscow, and probably launched a spring offensive deep into Russia, the Russians eventually would eventually have been defeated, now Hitler could turn his attention to the US....  Knowing what was comeing we would have been prepareing for a German invasionb for years, or porders would be fortified, and well laid defenses in place, and our troops already Veterans after defeating Japan, by this time the Manhatten project would also have been completed, and there would be a small number of Atomic bombs ready, and all the millitary build up, and technology we had at the end of the Real Word War 2 would also be present, the Germans would have to cross the Atlantic Ocean to get to us, and we'de see them comeing, and would have a nasty surprise instore for there fleet in the belly of a B-29, the Germans invasion fleet, which would also be of epic proportions would have recieved the first use of an Atomic Bomb in the history of Warfare, any remaining ships would be easily crushed by our Navy, and any groud troops quickly dealt with, eventually we would have launched an invasion of Europe, and haveing a Nuclear Monopoly, it would be easy work....

As I said though I don't think thats a likely scenario in all likelyhood we would have moved to assist the British, though possibly in a more limited fashion than we did before, atleast untill we finnished with Japan, but in all likelyhood the bulk of the War would be much like it was in the first place....

Hitler`s plans to strike the US were nebulous simply because it was more retaliation for our Lend Lease program. That program was blatantly illegal under international law at the time. However, Roosevelt sold it to Congress as a way to keep America out of the war. It might have worked until most of continental europe folded up like a lawn chair. Remember, lend lease goods had to be transported in belligerent vessels, not american;there by preventing another Lusitania incident. Hitler was also smart not to repeat Zimmerman`s mistake of trying to goad Mexico into attacking the US. That was the real reason we entered WW 1.

Secondly, by the time Germany was ready to strike the US the two ocean Navy would have been completed. We would have had much greater naval strength than Germany, Italy, and Vichy France combined. Added to that, there only a few transatlantic islands that could have been used as advance bases. The Germans couldn`t cross the English Channel with an invasion force. They certainly couldn`t cross the Atlantic.