I know the 10 volume history of "Germany in the Second World War" but I have not found time to read it in detail since it is over 12.000 pages, not always in an easy language.
https://en.wikipedia.org/wiki/Germany_and_the_Second_World_War
Have you read them? Can you give some details?
I have not read all of them, of course, but I have read Volume IV "The Attack on the Soviet Union" in the process of writing my second book on the 1941 Campaign. Chapter VII (pp 481 - 524) is entirely on "Operation Barbarossa as a War of Conquest and Annihilation" and includes sections on:
Regulation of SS Activity in the Operations Area of the Army - because the army provided the Einsatzgruppen with vehicles, manpower, rations, supplies and other support.
Hitler's Ideological Intentions Translated into Orders - by the Wehrmacht, including the order that exempted Wehrmacht personnel from ordinary military justice for crimes committed against the civilian population. Even German officers protested against this one, because it made 'murder' of prisoners and civilians virtually unpunishable and was bad for discipline.
Preparations for the War of Annihilation and the Attitude of Military Leaders - which lays out specific orders and directives for the (illegal) 'extermination' of civilians, commissars, and the taking and murdering of hostages - all of which were piously denied by the surviving Wehrmacht officers after the war, and all of which were War Crimes under the international agreements at Geneva and the Hague.
In addition, I have read and translated the War Diaries (
Kriegstagebuchen) of the German 4th Army, 3rd and 4th Panzer Groups, XXXX, XXXXI, XXXVI, LVII Panzer Corps, V, VII, and XIII Army Corps, 1st, 2nd, 5th, 11th, and 20th Panzer Divisions, 36th Infantry Division (Mtz), and 7th, 34th, 35th, 98th, 106th, and 258th Infantry Divisions of the German Army, and in those documents just for the months of October through December 1941 the German Army units themselves record instances of:
"using prisoners to clear minefields"
"organizing rations from the villages" (in fact, as the Chapters in DiZW Vol IV indicate, the German military was expected to 'live off the land' throughout the eastern campaign)
"seizing houses and driving the inhabitants into the forests" (in December in temperatures of - 30 degrees)
"seizing the farm carts
and their drivers to supplement the supply columns"
These steps, taken by numerous German Army Divisions are all in violation of International Law.
I read some books by Ian Kershaw like the Hitler biography and "The Nazi Dictatorship", but also books like Adam Tooze "The Wages of Destruction" (which was recommended in the HOI2-Forum many years ago) or Keegan (WW1, WW2)
I suggest in also (and all in English!):
Craig Luther
Barbarossa Unleashed
Robert Citino
Death of the Wehrmacht,
The Wehrmacht Retreats, and
The Wehrmacht's Last Stand
Finally, for a 'comparative study', I suggest Frank Ellis
Barbarossa 1941: Reframing Hitler's Invasion of Stalin's Soviet Empire, in which Ellis tries to make the case that the German activities were not that different from those of Stalin's Red Army and NKVD, but in the process lays out a pretty complete list of War Crimes committed by the German military in 1941.
I apologize that most all my sources are on the Eastern Front, but that has been my primary field of research for the past 5 years, so that's what I'm most familiar with.
I have not gone into any detail on the most massive war crime of all committed entirely by the German military, the systematic murder by starvation, shooting and neglect of over 2,000,0000 Soviet prisoners of war in 1941 - before any of the survivors ever made it back to Germany and the SS-run camps there.
At the time of 2nd world war, the german population was about 80 million people. Almost all male persons capable of fighting, around 20 million men, were mobilized between 1939 and 1945. With such a mass of people it is difficult to judge. Atrocities should not only be rated by absolute numbers but also in relation to duration, conditions (e.g. partisan wars) and number of total soldiers in a theater.
All War is an Atrocity; or to quote Sherman's entire phrase: "War is Hell and you cannot refine it."
BUT the systematic commission of War Crimes by a military force, and especially the commission of crimes which have a negative effect on its own capabilities (as when the Germans went looking to use Soviet POWs as slave labor in 1942, and discovered that most of them were already dead or dying - oops!), is an act of both Atrocity and Stupidity, and if the former may or may not be punished by human institutions, the latter always is, by that Homicidal (W)itch, Mother Nature if no one else.
I have little good to say about Iosif Stalin, but he summed up the massive German mistake in one phrase:
"They say they want a War of Annihilation: then they shall have it."
- And so they did.