The odds against were formidable. Although Army Group Center had been in Smolensk in August, no offensive action was taken toward Moscow. Hitler, called in to referee an argument among his generals ruled that the Army Group was to go over to the defensive, while half of its armored fist, the Second Panzer Army [Guderian] was to swing south and link up with First Panzer Army [von Kleist], to encircle some 660,000 Russians in what has become known as the Kiev Encirclement.
By the time Guderian re-deployed north it was late September. Despite the oncome of Autumn, Hitler and his generals [though not all his generals] decided to take Moscow that year. Operation Typhun was born.
The operation, initially, was a staggering success. Twin encirclements at Bryansk and Vyazma. bagged hundreds of thousands of Red prisoners. But then the rains came, the roads turned to a morass, and the attack slowed, first to a crawl, then to a halt. And the Germans waited for the ground to freeze, so it would carry their tanks. When it did, one of the coldest winters of the century broke on Russia. And with that came the realization that the Wehrmacht was totally unprepared for a winter war. All the machinery [tanks, guns, vehicles, aircraft] lacked oil, hydraulic fluid, and lubricants that could stand up to the weather. None of the troops had winter uniforms. The railheads were too far behind the lines [Russian RR gage was different than Europe's so the Germans had had to relay all the track], the supply system was choked with parts for trucks from countries like France [3d Panzer Army's truck establishment was almost 50% French], and inadequate reserves were available. Still the Germans advanced. Guderian tried to take Tula [he failed]. Hoth came from the northwest of Moscow [he failed]. The closest the Germans got was 28 miles from the Kremlin. And then Georgi Zhukov launched a surprise counter-offensive on a front over 100 miles long. the Germans broke, and fled.
Several of Hitler's generals counseled withdrawal to western Russia. Hitler ordered his troops to stand fast. Several generals disobeyed the order and retreated, others were pushed back involuntarily. But for Stalin's insistence that the offensive be widened, with a resulting dissipation, it would have been worse. As it was, the Germans wwere forced back to the environs of Smolensk, where they had started.
Hitler relieved the Army's C in C, Brauchitsch, and assumed the position himself. He also relieved his three Army Group commanders [Lieb. Bock and Rundstedt], and a group of lower ranking generals [including Guderian]. the Germans lost [temporarily] the initiative. They lost Moscow [and never threatened it again]. But most importantly, they lost the myth of invincibility they had gained in three years of war.