"I Wouldn't Have Started This War"
Hitler told tank commander Heinz Guderian about one and a half months into the war that had begun on June 22 seventy-five years ago, that had he believed Guderian's prewar statistics on Soviet tank availability, he might not have invaded.
The Soviets indeed had a lot of tanks and armored vehicles--more in fact than all other countries combined. (Yes, that's right.) But early in the war they did not know how to use them, and their tank drivers were in many cases mere novices with only a few hours of training.
The Germans had to make use of their superior training and tactical skill in order to achieve a victory before the Soviets could learn enough to make proper use of their weapons and build new ones.
The Germans failed.
They were slowed by logistics. (Quartermaster General Wagner told his superiors in the German General Staff well before the invasion was launched that he could not provide enough supplies for an advance that would penetrate all the way to Moscow. No one listened.)
They were slowed by the bad Russian roads (only 5% were sealed) that choked tanks and trucks with dust and sand when the weather was good and with mud when it rained. (Indeed, the Russians had traditionally identified part of the year as the "roadless" period.)
They were slowed by the need to lay new railroad track. (The Russian track width was wider than that of the Germans, so that, unless they captured Russian rolling stock, the invaders had to knock the pins out of existing rails in order to narrow the road bed enough for German rolling stock.)
They were slowed by the fanatical bravery of all-too-often badly commanded Soviet troops.
Finally, they were slowed by the terrible winter of 1941-1942, which came a mite earlier than expected.
By December, the invasion was stalled, and the Russians had time to regroup, ponder the lessons of June-December period, and, most importantly, begin to turn out more weapons.
They had dis-assembled whole factories (about 1,500 major ones and thousands of smaller ones) located in the path of the German invader and trans-shipped them to the safety of the Urals, where they were re-assembled with astonishing speed.
They then had to re-think their approach to production. Whereas, in peacetime, they made many tank models, now, in order to maximize production runs, they could only make one model each of light, medium and heavy tank.
They also quickly figured out that it made no sense to use tank components that lasted longer than the average life of the entire vehicle.
The average life of a tank engaged in battle on the Russian front was a mere fourteen hours. So the Soviets could use much cheaper components and machine to rougher tolerances than was previously thought.
The result was a staggering increase in output. From 1941 to war's end, the Soviets turned out over 100,000 tanks. That, believe it or not, was about the same total produced by the USA. Most importantly, it was more than double the tank output of the Germans, who had a craft, as opposed to a mass-production, approach to tank manufacture. Whereas the Soviets basically confined themselves to the three tank models, the Germans had nearly fifty.
Contrary to what the leaders of USA, Britain, and of course Germany expected, the Soviets withstood the 1941 onslaught and turned the tide as early as 1943. By the time, the western Allies landed in Normandy on June 6, 1944, the Russians had already, in Churchill's words, "kicked the guts out of the German Wehrmacht."
Their battlefield triumph began on the factory floor.