At the end of October 1941, the condition of the German Army in the Soviet Union
was grim. The 101 infantry divisions in the East had a fighting strength
equivalent to 65 divisions at full strength, while the 17 panzer divisions had
been reduced to a fighting strength of the equivalent of six at full strength.
Guderian, who had earlier been so enthusiastic about attacking Moscow, argued
that his army
was incapable of achieving its objectives. One of his panzer
corps, for example, had only 50 tanks left out of a full establishment of 600.
Map courtesy of Wikipedia.
The onset of the cold weather in November brought even greater hardship to the troops. Guderian again: "The icy cold, the lack of shelter, the shortage of clothing, the heavy losses of men and equipment, the wretched state of our fuel supplies, all this makes the duties of a commander a misery, and the longer it goes on the more I am crushed by the responsibility I have to bear."By December, the Russians had started to counter-attack the Germans. In just 20 days of the second offensive, the Germans lost 155,000 men (killed, wounded or a victim of frostbite), about 800 tanks and 300 artillery guns. The failure of German forces at Moscow doomed Germany to fighting a prolonged struggle on the Eastern Front. This part of the war would consume the vast majority of Germany's manpower and resources for the remainder of the conflict.
Video courtesy of The Armchair Historian.
Information from ThoughtCo and Real Clear History.