The amount of support Russia was getting from the West during that six months was minimal, yet Russia stops the Germans.
At that point, unless Germany obtained oil from the Mid-East (Britain would have had to agree) or the US (FDR would have had to agree), Germany in 1942 would be facing the same situation it had in real life. No fuel for any real operations, Stalingrad was attacked for it was the only area in Russia that Germany could attack. The Russians had more then enough troops between the German Forces in Russia and Moscow, and the Tank Factories that had been moved in the fall of 1941 were now in secure positions East of the Ural Mountains.
Stalin had planned on a war with Germany in 1942 NOT 1941. Thus he was unprepared for the June 1941 attack. Stalin refused to permit any of troops to retreat in 1941, thus ensuring their capture. In 1942 Stalin was NOT making that mistake, when the Germans headed for Stalingrad, Russians forces retreated rather then be captured. The "Goal" was NOT Stalingrad but the oil fields in the Caspian sea area. German forces never reached it. One of the reason is the lack of fuel.
As to what the US and Britain was doing in 1941 and 1942 that had any affect on the German War Effort (The air attacks on Germany from Britain was actually helping the Germans. The German people did NOT like to move, they wanted to stay in the same neighborhood their grew up in. The newer factories were in the Suburbs and the workers just refused to move to the new work sites, they stayed in their old neighborhoods. The bombing forced them to leave their old neighborhoods to the new homes and jobs in the Suburbs. Thus in the after war analysis of the Allied Bombing campaign, it was viewed as a failure. The successes were less then the results of the Germans moving to the Suburbs were the new factories were located. These Factories were disbursed and thus impossible to hit with night attacks (Favored by the British) and even difficult to hit in daylight air Attacks (Which the Americans Favored).
As to land warfare, Hitler had taken the Balkans in the Spring of 1941. He had minimal troops in Western Europe, the French were NOT yet into any Resistance movement. The first real Resistance movement came out of Yugoslavia and that was the result of the Germans having to release the whole Yugoslavian army after the Germans took Yugoslavia and Greece in the Spring of 1941 (And the German Troops were scheduled to be part of the German Invasion force into Russia so had to leave the Balkans almost as soon as the Germans Took it).
Rommel was running around in North Africa but with only two German Divisions (And one of these, the 5th "Light" Division was something formed out of various previously unattached army units), the rest of his forces were Italians (The Italian troops had a good reputation in the first part of the war, the Italian army Leadership were incompetent, but the troops were good and did while under Rommel).
Thus Germany had minimum troops located outside the Russian Front in 1941. Germany sent into Russia 154 Divisions (For comparison the US army only fielded 90 and the US Marines 10 for a total of 100 Divisions TOTAL). During the 1940 Attack on France, Germany only had a total of 157. This 157 Divisions does NOT count SS or Luftwaffe divisions (Both did not exist in 1940, but came into existence as WWII went on). In addition to the Two Divisions under Rommel, one more division was occupying Norway (Through a German Division marched through Sweden from Norway to Finland as part of Operation Barbarossa, this was done with Swedish permission). Some divisions were kept in the Balkans (including Greece and Crete) and France, but since no one was doing any real partisan fighting at the time in any of these countries, German troops were kept to a Minimum (Italian Troops were used to occupy most of the Balkans and Greece for Example).
The actual force made it the largest invasion force in History "Over 4.5 million troops of the Axis powers invaded the USSR along a 2,900 km (1,800 mi) front. In addition to the large number of troops, it also involved 600,000 motor vehicles and 750,000 horses."
http://en.wikipedia.org/wiki/Operation_Barbarossa#cite_ref-11Compared that to Desert Storm either the largest or second largest single military action in History.
"The Coalition committed 540,000 troops, and a further 100,000 Turkish troops were deployed along the Turkish-Iraqi border. This caused a significant force dilution of the Iraqi military by forcing it to deploy its forces along all its borders. This allowed the main thrust by the U.S. to possess not only a significant technological advantage, but also a numerical superiority."http://en.wikipedia.org/wiki/Gulf_WarDesert Storm is either the largest single action or the second largest. Operation Michael (The German 1918 Spring Offensive) is the other contender for that title. The debate is comparing a WWI army with a 1990 Army and thus which was the "larger" attack. Desert Storm had way more Aircraft and tanks then Operation Michael, but Michael had a lot more men, thus the debate which one was larger. More a academic debate but it is the contender for the title of single largest Military operations:
The attacking armies were spread along a 43 mile front between Arras, St. Quentin and La Fère. Ludendorff had assembled a force of 74 Divisions, 6600 artillery pieces, 3500 mortars and 326 fighter aircraft.... The average strength of a German Division in 1918 stood at 12,300 men, 3000 horses, 48 artillery pieces, 120 mortars, 78 heavy machine guns, 144 light machine guns, and 6–12 trucks.http://en.wikipedia.org/wiki/Operation_MichaelMy point is to show how powerful Operation Barbarossa was. Operation Barbarossa consisted of three attacks, all smaller then Operation Michael of 20 years before (and smaller then the Allied attack in Desert Storm) but when you view all three attacks together larger. It was a massive operation. The number of German Divisions NOT involved is less then a dozen. Britain was NOT capable of landing any sizable number of troops in the 1941-1943 period and almost all of the British troops were in Egypt, Iraq, India or the Far East. With the failure to gain air superiority over Britain a German invasion of Britain was Impossible so Britain was sending its troops where they could do some good (The US sent to Britain the 29th Division in 1942, more to show US support for Britain then any real Military purpose, the regimental joke was the 29th Division and the British Home Guard were the only land forces in Britain to stop any German invasion).
If you look at the 154 German Division in 1939 (More Divisions would be formed, but German Practice was NOT to send replacements to existing divisions, but to raise whole new division with cadre made up of older divisions that were broken up).
For more on the Afrika Korp:
http://en.wikipedia.org/wiki/Afrika_KorpsThe Invasion of Russia:
http://en.wikipedia.org/wiki/Operation_BarbarossaThe Battle of France:
http://en.wikipedia.org/wiki/Battle_of_FranceSorry, the whole premise is based on Hitler having access to oil. Before his invasion of Russian his main source of oil was Russia. The invasion cut off that supply. Hitler had six months to take Russia and if he failed, the Russians would slowly wear German Down (Which is what the Russian did after 1941). The only way Germany could have stopped the Russian onslaught was with tanks and mobile infantry, but to use either effectively you needed access to oil. During 1942 a German Infantry Division had to use 10% of what it used during peace time. This was to provide oil to the Armor Units and the Air Force. Civilians were even further down the priority list for fuel. As the war progressed Germany use of Horse increased (causing horse shortages throughout Europe for Horse died like flies in Russia). Soviet Forces actually decreased their use of horses as the war went on. Horses were still the main means of supplies to troops on the line, but only from a supply point where trucks would haul the supplies from the nearest rail head (a lot of these trucks were American made, but Russia was making just under half of the trucks they were using).
Given Stalin's disposition and nature, once he had the German army on the rope he would have drove home his army. Slowly the Russian Army would have destroyed the German Army. Victory may have had to wait till 1946, but it would have been Stalin's UNLESS HITLER OBTAIN A SOURCE OF OIL. At that point of History, Hitler could get his oil from the #1 oil exporter of that time period (The US), or the then new fields in the Middle East (Controlled by Britain), the Dutch East Indies (Under US influence or Japanese control) or Russia (The North Sea was NOT drill-able at that time period, not found to be a good oil field till the 1960s).
Without Oil Germany under Hitler was dead. Thus the question is NOT that Britain would have signed a peace treaty with Hitler in late 1940 or early 1941 (There is some evidence that such a peace treaty was being discussed but FDR killed it by telling Churchill if a peace treaty was signed FDR would cut off all aid. That threat about a peace treaty between Germany and Britain would have been enough to kill that peace treaty. Churchill would have viewed such a peace treaty as a truce and the situation between Germany and Britain would have become a "Cold War" and in such a situation Britain needed American Aid. Thus any talk of a peace treaty died by the spring of 1941 (The Bismark being sent out to sea in May 1941 may have been a way of Hitler telling Britain. Germany know British greatest weakness, all we have to do is get one battleship in a convey and you will be destroyed). Britain needed raw material and food from the US to survive and if the Convoy system was destroyed, Britain would have had to surrender.
My point is Germany needed oil once Germany invaded Russia. Would FDR permit Britain to supply the oil? I do not think so even if Britain signed a peace treaty with Germany. Without oil Germany would lose to Russia sooner or later and thus we would have ended up in the Post WWII situation sooner or later. The only way out of that situation would have been had Hitler NOT invaded Russia. Hitler would have had access to oil and thus in a strong position. If Russia even cut Germany off, Hitler could have pulled the Communist Card into the US and ask FDR to supply him the oil. If Britain could object but given the Anti-Communist tendency in the US, FDR would have shipped the oil and Britain would have signed a peace treaty to leave it flow by. FDR would only have shipped enough oil to keep the Germany Army strong enough to stop any Russian invasion thus no post war prosperity and sooner or later Hitler would have died and with his death Nazism would have died out.
And here is a thought, what if Stalin had attacked first? The theory is that the reasons the Germans were so successful in 1941 was they had attacked a Soviet Army geared to ATTACK the Germans NOT Geared for any defensive action. In simple terms, had the Soviets Attack the Germans something like what happened to the Russian would have happened to the Germans. Furthermore Soviet Armor was better then the Germans (Through HOW to use such army was inferior and most Russian Army was older then the excellent T-34) and the Soviet Union had more planes (Through at that time period inferior to the Germans, but the Russian RAT, while inferior, had out fought the ME-109 in Spain just a few years before, through the RAT was at the end of its development life, while the ME 109 was at the start of its development life).
Could the Germany Army stop such an attack if Stalin had hit first? A good question for one of the reasons Stalin was able to survive was the huge distance between what is now Poland and Moscow. Berlin was and is closer WITH better roads between Berlin and the Border and Moscow and that border.
http://en.wikipedia.org/wiki/Stalin%27s_Missed_Chance