The German tanks were unstoppable. During the first 7 days of the invasion they penetrated 300 km into the Soviet territory - 1/3 distance to Moscow

Battle of Moscow

By November of 1941, Russia was in dire straits. Hitler declared that the war had been won, and cited the evidence: 2 million Soviet prisoners, 22,000 artillery pieces seized or smashed, 18,000 tanks destroyed, 14,500 aircraft shot down. The German army was just 10 miles away from Moscow, and the Soviets had only 90,000 men and 150 tanks left to defend it. The world regarded Moscow surrender as inevitable. To cheer people up, Stalin gave a military parade. Photo: These troops went into the battle straight from the Red Square (Moscow, November 7, 1941):

Desperate times required desperate measures. The Russians trained dogs to run under the German tanks in suicide attacks. Photo: dogs, wrapped in explosives, are walking into the battle (Moscow, 1941)

In December of 1941, the temperature fell to -35 C (-30 Fahrenheit), unusually low even for Russia. The German army was unprepared, and 130,000 cases of frostbite weakened its front line troops:

Fresh, well-equipped troops pushed the exhausted Germans back by 100-200 km. This was the first major defeat suffered by the German army in WW2, and the bloodiest battle to date: 1 million soldiers lost their lives in the Battle of Moscow. Photo: German soldiers surrendering (Moscow, January 1942)