The first part of this looked mostly at the lead-up to Barbarossa, the German invasion of the Soviet Union, with only a few minor incursions into the actual invasion.
How was World War II a team effort in the last half of 1941 and early 1942, after the Germans invaded the Soviet Union? The Soviet Union was certainly doing the vast majority of the ground fighting at this point, with the vast majority of the German panzer divisions and the Luftwaffe committed in the east.
The Germans were in a war of attrition in the east, and even in those early days of the invasion, the Germans lost a horrendous amount of men and material. David Glantz gives a partial list of the men and material the Germans lost from the start of the invasion until November 1942. The Soviets were doing the bulk of the fighting and inflicting the bulk of the loses, while losing men and material at a high multiple of German losses. The Allies were fighting hard too, but their victories and losses seem like side shows in comparison to the huge number of divisions on both sides of the eastern front, the huge number of tanks and planes produced and destroyed.
Even before the Soviets encircled the German sixth army at Stalingrad, the Germans had suffered around a million casualties--dead or wounded. They had lost around four thousand planes. That had to have consumed a huge number of pilots who would have otherwise been available to fight the US and British air offensive over Germany. Also, when the Soviets surrounded the sixth army at Stalingrad, they forced the Germans to bring in their "school flights"--partly trained pilots and instructors, along with their equipment--for the airlift. The huge aircraft losses at Stalingrad crippled the German pilot training program as it was just recovering from losses in the airborne invasions of Holland and Crete, cutting into Germany's supply of new pilots at the worst possible time, when the western allies were gearing up for their air offensive over Germany.
So where does the team effort bit come in during this period? What did the Allies contribute? Several things, actually. Not many German divisions were actually fighting the Allies, but a lot of German divisions were tied up guarding against British or American invasion in the west. These were usually not first-rate divisions, but they would have probably done better than the Italian and Romanian divisions on the flanks of Stalingrad, for example.
How many German divisions were tied up in guarding against attacks in the west? A surprising number. Norway alone tied up more Germans than were surrounded at Stalingrad, though the quality and equipment of those troops was by no means comparable. The occupation of France also tied down a large and growing number of German troops. The Mediterranean theater was less of a drain in terms of manpower, at least until the Italian surrender, but the war there required a huge amount of logistics support--scarce oil, scarce air transport, scarce trucks to get fuel across the long stretches of desert from port facilities and railheads. It took far more German resources to support a division at the front line in North Africa than it usually did in the Soviet Union.
Direct British and US supply of tanks and aircraft to the Soviet Union was huge in absolute terms, but not in proportion to Soviet production and much of it came after the Soviet Union had weathered the worst of the German invasion. The Western Allies sent a little over eleven thousand tanks and another couple thousand self-propelled guns--enough to equip the equivalent of roughly sixty German panzer divisions, as many tanks as the Germans produced in 1943 and two-thirds as many as they produced in 1944.
At the same time, the Soviets produced considerably more T-34s every year after 1941 than they received in total Allied tanks. Lend Lease tanks were well under twenty percent of the total Soviet tank force and many of them were obsolete by eastern front standards. The Western Allies sent over twenty-one thousand planes to the Soviets, and those planes played a somewhat bigger role in the Soviet air battle than the tanks.
If you've researched the Eastern Front, you've probably heard most of that before. What kinds of team effort do most people miss?
1) The elephant in the room: The Western Allies kept Germany from accessing the rest of the world's raw materials. Most of the time that was by naval blockade, but sometimes it was by cornering the supply of vital raw materials in neutral European countries like Portugal and Turkey. Imagine a World War II where the western allies decided to remain neutral in the war between Germany and the Soviet Union. The Germans could buy or barter for Mexican oil as they did before the start of World War II. They could buy iron and nickel and chromium and bauxite and natural rubber from any country in the world willing to sell it to them. All the enormous effort that the Germans put into making ersatz materials could have been used to build tanks and planes and artillery, with the only limit being the German economy's ability to pay for the material.
That's not a trivial limitation, of course. The Germans were always short of hard currency before the war and would have quickly run into limitations after they invaded the Soviet Union. At the same time, they could have imported material to fill in the worst of their gaps.
Granted, a scenario where the west decided to sit out the German/Soviet war isn't likely, but if we're purely trying to figure out relative contributions, the British and American blockade of Germany played a major role in depressing German military production.
2) Throughout the war, the Germans had to look over their shoulders at an approaching avalanche of US men and material. That meant that the Germans knew they had a limited amount of time to defeat the Soviet Union. The Nazi hierarchy reacted to that closing time window by a lot of wishful thinking, seeing victory in the Soviet Union when objectively it wasn't there and they had the resources to know the Soviets weren't beaten. That pattern of wishful thinking started even before the invasion began, when the Germans produced the munitions and equipment they thought was necessary to beat the Soviet Union, then, before the invasion even started, switched production over to a mix intended to prepare for battle against the US and Britain. It continued through much of the early part of the war, with Hitler holding back tanks and tank engines throughout the summer of 1941 to build up for the coming battle against the Anglo-Americans. Even in 1942, Hitler saw victory after the early summer encirclements and moved key elite units from the eastern front to prepare for the Allies. In the leadup to Stalingrad, he could airlift whole divisions to North Africa and launch a lightning invasion of Vichy France to counter Operation Torch, while leaving sixth army's flanks to be guarded by demonstrably inadequate Romanian and Italian troops, with only threadbare backup from German units that had been bled white and given few, if any replacements.
3) The Allies filled crucial gaps in the Soviet economy. The Soviets did a miraculous job of moving key industrial plants out of the way of the German advance, but losing territory where nearly half of pre-invasion Soviet industrial activity happened caused important gaps that the Allies filled.
a) Food. The Ukraine was the breadbasket of the pre-invasion Soviet Union. The Soviets made an enormous effort to get food and farming resources out of threatened territory and to destroy anything they couldn't take with them. They were generally very successful in doing that. Instead of finding rich, exploitable farmland, the Germans often found lands where the grain had been hastily harvested and sent east, along with tractors, farm animals and able-bodied men. All of that effort to remove food supplies complicated the German advance because the Germans had expected to feed their armies by seizing food. To a certain extent they did, but the Soviets made it as difficult as they could, even destroying stocks of food they couldn't get out. This was the Soviet system at its most ruthlessly practical--they were leaving millions of Soviet citizens with little food for the coming winter.
At the same time, no matter how ruthless and efficient the Soviets were, they couldn't take the Ukraine's farmland or climate with them and without the land that they lost to the Germans, the Soviets couldn't feed the population already in unoccupied parts of the Soviet Union, much less the thirty million Soviet citizens that they evacuated in front of the German advance. Using the 1941 harvest and slaughtering livestock could provide a short-term solution, but when those stocks were exhausted, Soviet citizens were going to go hungry and they did, not just in Leningrad but in the rest of the country. When the Soviets released several tens of thousands of Polish prisoners of war to the Allies in 1942, many of them were so malnourished that it took months to get them back in fighting shape. The western Allies protested the condition of the men, but eventually had to concede that they hadn't been fed significantly worse than Soviet citizen outside the military and vital war industries. There simply wasn't enough food to go around and the Soviet Union was on the edge of starvation.
The western allies, especially the US, had plenty of food and they sent a lot of it to the Soviets. They didn't single-handedly stave off Soviet starvation, but they helped a lot. Enough American food came in to keep a million Soviet soldiers supplied. That helped substantially. If that food hadn't come, the Soviet soldiers would have still been fed, but a lot of Soviets outside the military and defense industry would have died of starvation or malnutrition.
b) Aviation gas: The US, alone of the World War II powers, could mass-produce 100 octane aviation gasoline. That gas gave planes that used it a major edge over planes that didn't. As a result, the US produced the vast majority of Soviet aviation gas, and provided additives to upgrade Soviet oil. At any given design level, US aviation gas allowed US and Soviet planes to fly further and faster than they could have otherwise.
c) Aluminum. The US provided over two thirds of the Soviet aluminum supply, vital to Soviet airplane production and for producing engines for Soviet T34 tanks.
d) Rubber: The Soviets had no native sources of rubber and their synthetic rubber efforts lagged behind those of the US and the Germans. As a result the Soviets were chronically short of rubber. That was a huge potential bottleneck. It was simply impossible to build World War II tanks, trucks and planes without rubber and lots of it. Planes averaged half a ton of rubber, while a tank took a ton. Add in tires for military trucks and airplanes and replacement tires for the trucks that kept the Soviet economy going, and you see the problem. The US sent as much as it could spare, with the amount increasing as the US synthetic rubber industry took off. In terms of tires alone, US Lend Lease to the Soviets totaled a little under 3.7 million units. That's a lot of vehicles driving a lot of miles.
e) Radios. Radios and other communication equipment were a huge force multiplier. In 1941 and through the summer of 1942, the Soviets didn't have enough of them. As a result, Soviets commanders often lost track of where parts of armies were and what was happening to them, often units as large as whole divisions. Where were they? What was happening to them? Were they still in the fight? Without that information the Soviets simply couldn't fight the kind of fast-moving war that the Germans forced on them. The US and Britain, with their advanced electronics industries, filled that gap. For example, the US sent over 380,000 field telephones and well over thirty five thousand radio stations.
f) Training tanks. A lot of the thousands of Lend Lease tanks never saw frontline service, but they did play a major role on the Eastern Front: training tank crews. The Soviets built their tanks the same way they ran most of the rest of the war--with a ruthless peculiarly Soviet type of rationality. They had plenty of raw materials but not a lot of skilled laborers. Given that combination, they built essentially disposable tanks. If a T-34 was unlikely to survive more than X hours at the front, the Soviets didn't build it to last more than X hours plus a small margin. Automotively, the few that didn't get knocked out by X hours were scrap--ready for a major rebuild at best or for scrap recycling. That approach meant that the Soviet could build a lot more tanks with a given number of person-hours and it didn't usually cost them much, because the tanks were usually knocked out by the Germans before they broke down anyway.
The problem though: how do you train tank drivers? Using Soviet tanks meant using a lot of them and leaving them as scrap. Using Lend Lease tanks was the ideal solution. Many of the wouldn't have lasted long on the Eastern Front battle zone, but could be driven a lot longer in training roles.
This is getting long, and we still haven't looked at the impact of the Western Air Offensive. More in a few weeks.