German power fell below a "critical mass" on the long Russian front.

Before Kursk, the Germans had just enough armor to cover the whole Russian front. It is something like 2626 km from Archangel to Astrakhan on today's roads, per the distance calculator, more in those days.

With the losses at Kursk, German armor could no longer cover the whole front. After Kursk, Manstein barely managed to repel a Soviet attack near the Black Sea region but while he did, the Soviets broke through just south of Kursk. These distances were too far apart for Manstein to cover with one mobile force. Because of this, the Soviets were able to successfully "echelon" their attacks, but it might not have been a problem if Manstein had two mobile forces in the two different places.

It should be pointed out that in 1940 the Soviet Union had a population of about 195,000,000, Germany had about 70,000,000. When Germany attacked, not every abled bodied citizen in the Soviet Union joined the armed forces in one day. All during the war, the Soviets could keep drafting more and more people from their larger population. They could replace their losses as fast, more or less, as the Germans could destroy them. Also, after Stalingrad, the Germans were losing territory/resources and the Soviet Union was gaining territory, though it would be time before they could reap the benefits of the resources.

I think the OP question is a legitimate one, and one that has been puzzling me too. I don't understand the irritated answers of many posters, or even the assumption of a hidden agenda (!). The question is clear.

In the period from the Battle of Kursk to June 1944 (before the start of Operation Bagration) the casualty ratio between Soviets and Germans is generally accepted to be 4-5 to 1. About 5 to 1 for tanks as pointed out above. In this period the Soviets were able to reconquer almost all Ukraine, and push back the Wehrmacht on other areas as well. In all this period the German army in Ukraine was always described - by the memories of the German generals as well - to be on the verge of collapse. Only the last spring offensive on the Romanian front failed. And yet, as pointed out by the OP, Soviet production + Land Lease was much less than 5 to 1.

Until spring 1944 the great majority of operational German AFVs were on the Eastern front. The Italian front was little more than a sideshow, and not conductive to armored operations, so the Germans didn't have many AFVs there. There were some panzer divisions in France, but they were sent there to refit, and generally recalled to the East in time of crisis. Only in the spring 1944 the Germans built up their panzer forces in France to face Overlord.

So apparently there is an anomaly here. If you pour out 2 times as many tanks as I do but I constantly destroy 4 times as much, you are getting weaker and I'm getting stronger, it's arithmetic. Yet at every offensive the Soviets were able to deploy the same or higher tank ratio, and keeping on pouring them out and pushing back the Germans relentlessly. For artillery the ratios are even more incredible.

In the air in 1943 Germans were at least holding their own, and sometimes were able to achieve local superiority, so Soviet air superiority shouldn't be a decisive factor in that period. Manpower discrepancy is easier to explain because the Soviets pursued a ruthless conscription policy, sending to the front masses of half-trained men, while women and children were working in the factories in conditions who would have been unbearable for Westerners and German civilians.

Yet, material superiority was the decisive factor in WW2. By that account, the war on the Eastern front from Kursk to Bagration should have been a stalemate, or at least not so catastrophic for the Germans as it was. It's not about 'not liking it', it's just an historical puzzle that deserves further investigation. None of the answers given above seem completely satisfactory and they skirt the main issue. Yet, after the opening of the archives, Soviet losses are well documented, so it seems it's not a case of overestimation.

My question is if the German losses aren't perhaps underestimated. Authors like Zetterling and Frankson seem to take German battle reports and documents at face value. Could it be that Germans tended to 'hide' the extent of their losses in their official documents? Maybe a possible explanation, as suggested by a poster, is the different way Germans and Soviets counted their material losses. Also, panzers damaged beyond the possibility of field repair often had to be sent back to Germany because of lack of adequate repair facilities closer to the front. That kept them out of the fight for many months, making them for practical purposes write-offs, even if they weren't counted as such. Still, I think it's an issue that deserves further attention.

Contrary to popular opinion, war is about destroying the enemy's willpower, not its manpower. Inflicting casualties is simply a means to an end. Once the enemy's willingness to engage is destroyed, so is its ability to win or even sustain combat.

Possibly through the entire war, but certainly through the end of 1943, Russian High Command knew full well that its soldiers were much poorly equipped, trained, and outfitted than the German troops they faced. They did however have two massive advantages: Far greater manpower reserves in the population, and the guarantee of Marshal Mud's appearance for about 6 weeks each spring and fall.

The first meant that the casualties required to fight a superior foe could possibly be sustained. The second meant that no how bad a campaign went for 16-18 weeks, the Germans would be halted for a six week respite twice a year.

At Kursk all the Soviets had to do hold their line long enough to eliminate enough enemy soldiers, or equipment, to halt the attacks. As it was, the Germans ran out of serviceable equipment before they ran out of men, but that was sufficient. The extremely short service interval for the new Panther tanks certainly helped in this regard.

For tank casualties, Thomas Jentz has a table Operational Status of Panzers on the Eastern Front, 1943 on page 110 of "Panzertruppen, vol. 2". Before Kursk, the tank totals were 2584 available and 2281 operational. A month later, the totals were 2471 and 1471, which includes some additional tanks. Therefore, the number of German tanks operational went down by about 800, which is roughly half the Soviet losses listed in the Wikipedia article.

The number of operational tanks never recovered in 1943, hitting a low spot of 605 at the end of September and recovering to 1043 at end of year, although the number of available tanks (present and not wrecked) bounced around 2000 for the rest of the year.

So, Kursk put over 800 tanks out of action, over a third of what they'd started with, and the repair depots were never able to catch up, what with losses from the Soviet offensives. That was significant.

(Jentz, in this book, covers tanks and some tank destroyers (the Jagdpanzers), but not the Sturmgeschutzen, which were owned by the artillery. It makes the figures somewhat difficult to compare sometimes.)

One reason that the arithmetic does not work that way is that there is a certain minimum number of troops you need to hold a 3000-kilometer front. Even if you improve your disadvantage, say, from 1:3 to 2:5, but your total number goes below that minimum, that means you have no troops to spare and concentrate for the offensive, but the enemy does.

Also, time was a very important issue. For Germany, the only chance of winning the war would be to score a quick decisive victory; just waiting would mean that they get outnumbered and outproduced, while running out of resources. It's not only about the growth of the Red Army: it the military power of Western allies would soon grow enough for operations like strategic bombing of German cities, the Invasion of Sicily and of Italy, and eventually D-Day. And indeed, Hitler soon had to divert about 1/5 of his entire army to Southern Europe to replace the Italians after Italy left the war. Also, time is not quite linear: if you fail in the summer, your next chance will be in winter, when the mud freezes. Which means a few more months in which the enemy will grow stronger.

Germany was fighting a multi-front war, whereas the Soviet Union was fighting on one (very large) front. They had been fully committed since Sept 1939 whereas the Soviets began fighting in earnest in the summer of 1941. When Barbarossa began the German army was already under-strength. Germany was also supplying their allies, whereas the Soviets were being supplied by their allies. Kursk was not representative of the casualty ratio of the Eastern Front which was closer to 2-to-1. Finally, be wary of simply lining up numbers of tanks.

Over-stretched

At the time of Kursk, had already fought in Poland (which was not the pushover it's made out to be), Norway, France, Yugoslavia, Greece, and Crete. They had to make good the losses from those campaigns, plus garrison all that territory, plus prepare for an invasion anywhere along the Mediterranean, Atlantic, and North Sea.

They were also fighting the Battle of the Atlantic, a significant drain on men and aircraft. They had just been defeated in North Africa. The Germans had been fighting an enormous war in the Soviet Union for two years. Their offensive capability had been ground up in broad and deep advances, and their finest army totally annihilated at Stalingrad.

Shortly after Kursk they had to contend with the invasion of Sicily, then Italy and the collapse of the Italians, and later the invasion of France. Plus Allied strategic bombing.

To say they were spread a bit thin is an understatement.

While total German tank strength was maintained at about 5000 to 6000, by 1944 about 1500 were in France and a few hundred in other theaters. The numbers here drawn from multiple sources show about 2500 German tanks on the Eastern Front, plus 1000 assault guns.

Tank Production

If you simply line up the numbers, the situation for Germany looks ok given their casualty rates. In 1943 the Germans produced 11,601 tank hulls whereas the Soviets produced 26,742. A 2.3:1 ratio which seems lower than overall casualty rates on the Eastern Front. Once you account that Germany only had about 60% of its army in the Soviet Union in 1943 now it's 3.8:1 which is very bad. It's when you look closer at what Germany is producing that things become disastrous.

German industry was so overstretched they continued to produce obsolete tank hulls rather than retool. One must keep this in mind when looking at German production numbers. For example, in 1943 Germany produced 11,601 tank hulls. But of those 3379 were Pz IIIs, 1,008 Pz 38ts, and 803 Pz IIs. Nearly 45% of their tank production was obsolete hulls.

They compensated for this somewhat by turning obsolete hulls into assault guns, tank destroyers, artillery, and anti-aircraft like the Marder, Grille, and StuG but these were not replacements for modern tanks.

In that same period the Soviets built 15,710 T-34s, 4,098 T-34 based assault guns, 719 KV and IS heavy tanks, 703 KV/IS based assault guns, and 3,348 light tanks and 2,109 light assault guns. This was something of a lull in Soviet heavy tank production, they would make 4,764 in 1944.

If we line up Soviet medium and heavy hulls with 60% of German Pz IV, Panther, and Tiger hulls things get dire. 6,320 vs 21,230 or 5.6:1. And that's before taking into account Lend-Lease tanks, about 7000 US and 5,218 British tanks over the course of the war. Now that 5:1 ratio at Kursk doesn't seem so bad.

This is a pretty crude analysis, but gives you some idea of the dire situation Germany was in.

Under-strength

From a production perspective, Germany began the war a few years ahead of schedule. When they invaded France in 1940 a significant bulk of their armor was still obsolete Panzer I and II tanks. At the start of Barbarossa they were still relying on the obsolescent Pz II and 38t tanks for the bulk of their tanks with insufficient Pz III and IVs. The Pz III was becoming obsolete itself. Germany would upgun the Pz IV, field the expensive Tiger, and design and begin production on the Panther.

Transport was insufficient for the long distances and bad roads they would encounter hampering their logistics. Petroleum was already becoming a limiting factor in German operations, that would only get worse and limit German training and mobility.

For Barbarossa, Germany committed 80% of their army, plus help from the Finns and Romanians, amounting to about 3.8 million men, 6800 armored vehicles (about 3500 tanks), and about 30,000 guns and mortars. The Soviets had 5.7 million men, 117,000 guns and mortars, and 25,700 mostly obsolete tanks.

But also consider that the Germans had been fighting for two years already at this point chewing up their reserves whereas the Soviet Union was just getting mobilized. Germany had a population of about 65 million whereas the Soviets had 196 million. The Soviets could and did replace casualties at a 3:1 ratio.

While the casualty lists for Barbarossa are staggering, their relative effect on the German army was much higher, plus the greater requirements of attacking. When Barbarossa began they had 163 divisions capable of offensive action. At the end of March 1942 they were down to 58. This greatly scaled back their operations. While Barbarossa attacked in three directions simultaneously, the Germans could only attack in one, south, in 1942. And while they made great territorial gains, it ground up their best offensive units.

To further underscore this, while on paper the German Army fielded 2.6 million soldiers in the East in Oct 1943, of that only about 1.2 million were combat soldiers. The rest were supply, security, and baggage train. With a 2000 km front, a single under-strength German division in 1943 had to cover 16 km.

Soviet military recruitment

German industry was still gearing up for "total war" when they launched Barbarossa, a combination of continuing to give lip service to the Versailles treaty, and also having to spend money on domestic projects. The Wehrmacht, too, was still building itself up in 1941 and was built for a short war. Thus the Germans were already overstretched when they invaded the Soviet Union and lacked reserves.

In contrast the Soviet Union had been preparing for war for a decade with 14 million reserves, former conscripts, 3 times the size of the invading German army. Thus they were able to rapidly replace loses with at least somewhat trained men. While the German army in the East always hovered at about 3-4 million men, the Soviets went from 5 at the start of the invasion, to 8 million at the end of 1941, and 11 million by the end of 1942. Thus even with 40% of its population under occupation in 1942, they could not only replace losses, but grow their army. They still outnumbered Germany 2-to-1.

By 1943 the bulk of Soviet production was reconstituted safely out of reach of German bombers, another shortcoming of the Wehrmacht was its lack of heavy strategic bombing capability. Meanwhile German industry was under increasing attack, shortages of fuel and materials were becoming worse, and it always remained something of an inefficient mess with multiple companies producing competing designs and set to fight one another for contracts.

Soviet counter-offensive

It's to be noted that the Germans were attacking at Kursk while the Soviets were defending. Defending means less movement which is less wear on vehicles, fuel, and supplies. But while Kursk was a last-ditch effort for the Germans, Soviet material superiority was so great they could both defend Kursk and prepare a counter-offensive. Even before the smoke of Kursk cleared, the Soviets were attacking the exhausted and thinned out Germans with 2.5 million men: Operation Kutuzov in the north and Operation Polkovodets Rumyantsev in the south. These were quickly followed by the Battle of Smolensk and Dnieper.

While these resulted in high Soviet casualties, and the Soviets did not get the encirclement they hoped for, they further depleted German front line units destroying their offensive capabilities. While the Germans could and did stage ferocious local counter-attacks and never broke, they no longer had the fuel, equipment, nor experienced men, to mass for an offensive. To do so would require thinning their already thin lines elsewhere and risk the very offensively capable Soviets breaking through. Any mobile forces had to be held in reserve to plug the gaps the Soviets were blowing in their lines.

Soviet losses and gains

While Soviet losses in these battles are spectacular, they are not representative of the Eastern Front as a whole. While the numbers are hard to pin down, Soviet military deaths are about 9 to 11 million with about 14 million wounded. German military deaths are about 5 million with about 7 million wounded. There's that 2-to-1 population ratio.

The astonishing 5:1 tank loss ratio was maintained through the war, though it dropped off severely to near 1:1 in 1945. A simple examination of the numbers shows how this was possible.

• Soviets start the war with 22,600 tanks.
• They produce 72,231 tanks.
• They receive 12,000 from lend-lease.
• They irrecoverably lose 83,500.

From a stock of 22,600 + 72,231 + 12,000 = 106,831 they lose 83,500 leaving 23,331 tanks at the end of the war. This is very close to the estimated 25,400 tank strength the Soviets had in 1945.

Conclusion

The Germany military was already overstretched when they launched Barbarossa in 1941 with insufficient transport, armor, and reserves. They expected a rapid collapse similar to France to win. When this did not happen it became a war of attrition with an enemy with much deeper reserves and fewer distractions. They were only able to keep up with loses by using lower quality troops and equipment, in particular cheaper, turret-less assault guns rather than real tanks. From 1943 on they had increasing commitments defending their empire draining resources from the Eastern front.

In contrast, due to years of conscription the Soviets started with a much larger army, more equipment, and deeper reserves to draw on. Despite horrendous losses in 1941 they were able to replace them from reserves and even grow their army. Even with 40% of their population in occupied territory they still outnumbered Germany 2-to-1 which matches the Soviet/German casualty ratio. While Germany was increasingly fighting on multiple fronts, the Soviets could focus on defeating the Germans. While Germany was being bombed and strangled and messing around with wonder weapons and complex designs, the reconstituted Soviet industry was safe behind the Urals and turning out brutally efficient equipment. While Germany had to supply its own allies, the Soviets were being supplied by theirs.

In 1941 the German army had the offensive power to attack on the entire Eastern Front. They took heavy loses they could only partially recover while facing a reconstituted and even larger Soviet army.

1942 required channeling their dwindling offensive capability into one front, the south through the Caucuses, grabbing much territory but leading to the devastating loss of an entire army they could not recover.

In 1943 they could manage one major offensive: Kursk. This was their last chance to win the war in the East before the inevitable Allied invasion in the West would further dilute their strength. When it failed, they were done.

See also

I'd recommend Military History Visualized's playlist on the Eastern Front for more detailed analysis and numbers.

I also drew from The Eastern Front, 1943-1944: The War in the East and on the Neighbouring Fronts much of which is available on Google Books.