Germany’s wars
In many ways Germany’s experience of the Second World War had a unique perspective. The British Empire and the United States of America, in the words of David Edgerton (2011), “fought a war of machines” with the majority of their effort being put into the Strategic Bombing Campaign and relatively little effort being put into a Land Campaign until June 1944. For Germany, this tied up a small Corps in the Western Desert in 1942, a single Army in Tunisia and Italy in 1943 and only substantial numbers of combat troops in 1944 by which time the Ostfront had been well and truly lost. So Germany fought, in effect two wars, a war of machines and high technology by using planes and U-Boats in the West and a war in the East that had many characteristics of the First World War, horses, artillery, infantry and trenches with a smattering of tanks. This dual nature of the war from the German perspective was reflected in their casualty rates with the Heer suffering the worst losses of the Wehrmacht and according to some estimates up to 80% of its losses occurring on the Ostfront. Even when the Allies landed in Normandy in June 1944, the German Army had been fighting for three years in Russia, had been in strategic retreat for a year and on 22 June 1944 would suffer its largest ever defeat. It was no longer the same army that had invaded Russia in 1941.
The Soviet and First World War losses compared
Given this difficulty in comparing two very different conflicts during the Second World War, there might be more value in comparing Soviet losses to the losses of the First World War because these armies directly engaged the German army in ground fighting over a sustained period. While there are technological differences between the two wars, in the Soviet-German War these are less and there are many occasions when fighting was very similar, such as the Rzhev salient.
The graph below shows in light blue the comparative numbers of men mobilised by each nation and the other colours represent the different types of losses suffered. The immediate impression gained from this graph is the extraordinary scale of both mobilisation and loss suffered by the Soviet Union, dwarfing all other combatants and illustrating that this event was a true outlier. Even when compared against the Imperial Russian Empire, which due to its larger geographic size had a similar population, there is little similarity and the Empire’s society collapsed into revolution with far fewer men mobilised and lost. Imperial Russia does not make a good comparison with the Soviet Union because most of their fighting was against the Austro-Hungarian Empire and there is considerable confusion over the losses towards the end of the war.
So it might be best to look at the British and French as a good comparison for the Soviet Union. Although smaller in terms of men mobilised and casualties, the proportions of these relative to the size of the armies might provide an indicator.
The graph below shows British casualties during the First World War and the pattern reflects the small force sent to France in 1914, its steady growth over 1915-1916 until the army reached its peak in 1917 and the casualty rates reflect this. However this pattern is not the same as that experienced by the Red Army in the Second World War.
This graph shows French casualties and as can be seen, the pattern of loss is a much closer match to Soviet experience with high losses in the early years due to tactical inexperience with lower, but still substantial losses for the rest of the war even during the Mutinies of 1917.
The other part of the equation to consider is the enemy losses and this graph shows the German losses on the Western Front incurred on the Franco-Belgian sector and the British-Portuguese sector (according to WSC losses due to American forces were no more than 100,000). The French represented a dangerous enemy to the Germans throughout the war even when the British army had grown to its full strength of 1.9 million in 1917-18 while the French field army had fallen from its high point of 1.9 million down to 1.6 million in 1918.
Comparing French and German losses side by side (this graph relates to losses on the battlefield as the German statistics do not cover deaths in hospital, deaths of POWs etc) we see an initial German superiority in exchange which gradually equalised over the course of the war. However the losses of 1914-15 demonstrate French troops readiness to die and be wounded in large numbers while the enemy invader was still on French soil and the costs of the tactical and strategic errors made at all levels of the French Army. By 1916 increasing French tactical skill and proper equipment enabled them to narrow the gap with the Germans gaining parity for the rest of the war.
As has been shown earlier, a direct comparison between the Soviet Red Army and the French Army is not possible due to the disparity in their mobilised strength - 35 million compared to 8 million or the size of their field armies - 6 million compared to 1.9 million. None the less their relative attributes compared to their losses might give some clues as to similarities or differences between the two armies. The dataset used for this study is taken from Krivosheev and Churchill and is shown below:
So the graph below takes the information from the table above and displays it in terms of losses (killed, missing and POWs) and wounded as a percentage of the strength of the field army for that year. If you like, the proportion of the army that were rendered ineffective and needed to be replaced or in the case of wounded recycled.
As this graph shows, there is quite a difference between the Soviet and French armies in the early years however both armies proportion of loss declines over the course of the war and reach similar levels by the end. Now while both armies squandered their troops in fruitless offensives (French) or in uncoordinated counter attacks (Soviet) in the first and second years of the war, only the Soviets lost substantial numbers as POWs to encirclement. If we remove the 3 million POWs in 1941 and 1 million in 1942 from the dataset perhaps we get a clearer picture of battlefield casualties. Of course the majority of these Soviet POWs would be starved to death by the German and then they would become permanent losses however their capture in the first place in the huge encirclements close to the border was a function of modern mechanised warfare not available to the Germans in the First World War.
As we can see the pattern of dead, missing and POWs "relative to the size of the field army" was very similar between the French in the First World War and the Soviets in the Second. Both follow a similar pattern of development during the war and end up at the same level. By contrast the wounded pattern is very different, with the French line following the dead, missing, POW pattern including a slight rise in 1918, while Soviet pattern shows substantial divergence until 1943 and then stability. (It has to be remembered that the Soviet lines for 1945 only cover 5 months of warfare in that year.) A curious feature that needs to be examined in more detail.
The next question to ask is whether this dataset shows statistical significance between the two sets of lines but it is a long time since I used a Chi-squared table and I seem to have mislaid my slide rule.
Sources:
For the Soviet Union the source used was G. F Krivosheev "Soviet casualties and combat losses in the twentieth century" Table 69, while recognising that this data might represent a minimum figure and that later studies might have raised the total from 8 million to as high as 13 million.
For the British Empire forces in France during the First World War the sources used were "Statistics of the military effort of the British Empire during the Great War, 1914-1920" (https://archive.org/details/statisticsofmili00grea/page/n4) p250 and the Official History of the Great War: Medical Services - Casualties and medical statistics of the Great War (https://babel.hathitrust.org/cgi/pt?id=uc1.$b744277) p108
For the French Forces, the sources used were "The World Crisis" by Winston S Churchill table Pertes des armees Francaises (nord-East et Orient) reparties par periodes p1424
For German Forces on the Western Front the sources used were "The World Crisis" by Winston S Churchill table German losses on the Western Front by main operations periods p1425 and Losses of men in the German land forces p1425