Their entire front against Russia was eventually reliant on their ability to drag heavy artillery and supplies through the dangerous mountain passes of the Carpathian mountains. An example of what they went through for their country: https://upload.wikimedia.org/wikipedia/commons/4/42/Wintersc...
Supply lines are the often unspoken critical pieces of the puzzles for any great war before mid-WW2. Poor logistical planning in their invasion of Russia was also was a major factor in why the Nazi's lost WW2 - which is where Germany really lost the war, the "war of the Atlantic" and later western front with the Americans was just the multi-year delayed wrapping up action where they had very little odds from the beginning.
This second book  has a great overview about why the Nazi's had actually lost the war by 1941 (and very obviously by 1942) due to poor logistical planning of Operation Barbarossa, largely due to the strategic planners overconfidence in the German superiority over Slavs after they swept the French/British out of Europe. The next 3yrs were just Hitler's delusions keeping it afloat.
If you think the roads in your town are poorly maintained, take a look at this example of Rasputitsa in the USSR. 
Yes, the people in the photographs are trying to pull that car down the road. Yes, that is indeed a road.
Soviet railroad gauges being incompatible with European rail gauges also did little to help German logistics. And later in the war, due to fuel shortages, more and more axis machinery had to be transported by draft-horse.
But the earlier half was largely a mix of WW1 esque supply logistics using horses and german automobiles struggling over poor Russian roads. The poor logistical planning I alluded to was largely underestimating how poor Russia's infrastructure was and overestimating the capabilities of Germans to overcome them.
Is it actually that rare to hear military histories avoid discussions of supply lines? It seems very common to me. The phrase "an army marches on its stomach" is in the popular imagination, right?
Even post-WWII, discussions of Vietnam usually talk about the Hồ Chí Minh trail, don't they?
EDIT: Actually, there's a more general question I've been wondering: What is a good way to figure out if something is common knowledge or not? I've occasionally found myself assuming something was common knowledge and while "No feigning surprise" is a useful rule to try to follow, it would be better if I had a way to train my intuition to be more accurate about how well-known facts are.
 https://jvns.ca/blog/2017/04/27/no-feigning-surprise/, though the rule should be "no acting surprised" because I think the common case of it is an expression of genuine surprise.
"When the planning started for the Gulf War, they told me I had to go and I could bring only one other of my officers with me. So I chose what any good general would do: my logistics officer"
To be picky, mules.