The German invasion of European Russia was a huge mistake for several reasons, the biggest being that Germany had insufficient forces to win in the first year. Another reason was the force disparity between the German and Russian armies there is also the almost total lack of realistic logistics planning on the part of the German High Command or OKH. The German army did not have contingency plans for a winter campaign and were thus caught flat-footed when Russia failed to capitulate in 1941; this lack of planning was despite the recommendations of such officers as Guderian and Manstein.
 Several strategic principals were violated both in the conception and during the execution of the campaign. These included concentration, mass, and unity of effort. The Germans did not have the forces to both guard their flanks and concentrate at their chosen decisive points. The lack of sufficient forces also caused them to sacrifice mass at critical sectors of the front and accept the tactical defensive because they simply could not attack everywhere at once. An example of this is the battle in the Yelnya salient in August and September of 1941, while the Smolensk battle was raging. They lacked unity of effort in that the different army groups competed for resources to accomplish too many objectives for the available forces. This caused a disjointed advance as armored forces jumped from place to place along the front.
 The German plan envisaged the total defeat of the Russian Army during the course of the initial battles, this calculation turned out to be optimistic. As conceived, the German army’s plan failed to accurately account for the amount of resistance they subsequently encountered in conquered areas. Instead they apparently believed that the Russian army would collapse and conquered areas would cheerfully submit to foreign domination. They also failed to realistically appreciate the distances involved in a campaign in European Russia and the wear this would place on vehicles. It was unrealistic in the extreme to expect the German army to be able to advance over 1,500 kilometers deep in a front almost 2,000 kilometers wide in a few months while simultaneously defeating an army almost twice the size of the invading force.
 German intelligence was faulty; they underestimated almost everything about the size of the Russian army. The Germans thought the Russians only had 5,000 tanks, instead the true number was somewhere between 10,000 and 20,000. They underestimated the size of the Russian field army by almost 100 divisions and did not take into account the combat experienced far eastern army, which they felt could not be deployed in time to affect the campaign.
 The most serious error committed by the German command was made by one man, Hitler, who lost his focus in the middle of the campaign and cost the advance on Moscow six weeks of good weather for a diversion to the south. The strategic focus was not maintained because Hitler wanted economic gains that would fall to him anyway were the campaign successfully concluded.
 One of the least convincing arguments against Barbarossa is that it committed Germany to a two front war, because if Germany had won the first year as they had planned or even the second year, there would have been no second front. There is no reason to believe that significant Japanese forces would not have swept into the Russian Far East in the event of a German victory in the west.
 Finally, while the German army perhaps could have brought the campaign to a successful conclusion, poor planning and bungled execution caused them to instead become engaged in a brutal slogging match they could not win. Though it took the Russians four years to defeat the Germans, the seeds of their victory were sown in 1941 by their successful retention of Moscow.
 Some further expansion on my thinking:
 I believe the Kiev and Smolensk operations were a mistake because they diverted forces from the decisive point. Moscow was then and is now the heart of Russia. Something like 80% of the transport links between European and Asian Russia go through Moscow and almost all the north south links. Once Moscow was taken, the rest of the country would have almost been fruit on the vine. The southern armies would have lost their source of supply while the northern armies would have lost their sources of manpower.
 The only chance Germany had to win the war against Russia was by taking Moscow. The armies around Kiev would have more than had their hands full dealing with Army Group South and any forces they could detach to attack Army group Center would have been at best small and ineffectual. The Germans amply demonstrated their mastery of maneuver versus Russian capabilities.
 List of sources:
 Erickson, John. The Road to Stalingrad. Reading, Berkshire, UK: Cox & Wyman Ltd., 2003
 Fugate, Bryan I. Operation Barbarossa: Strategy and Tactics on the Eastern Front, 1941. Novato, CA, Presidio Press, 1984
 Barnett, Corelli, ed. Hitler’s Generals. New York, NY: Grove Weidenfeld, 1989
I think that there is a more important factor.
The whole German enterprise was criminal and murderous on an unimaginable scale.
They unleashed a gigantic killing machine on a people who had been at peace.
By some estimates Russia lost something in the order of 19,000 people a day throughout the duration of this conflict.
Surely this undermined any moral conviction in the German military about the “justice” of their cause.
They had no honourable business to be in Russia.
And knew it.
Whatever the moral flaws of the Soviet govenment, ordinary Russians had no doubts about the real issue.
They were fighting for their lives.
In this piece I am analyzing the Russian campaign along purely military lines. I try not to make moral judgments in my writing. I leave that to my readers; they have minds of their own and do not need me to push my moral opinions on them.