History of the War, Part 2

Chapter Four. "The History of the Nazi German Offensive."
On June 28, 1919, a peace treaty was signed between Germany and the USSR. On September 1, 1939, Nazi Germany invaded Poland. In 1941, the Nazis reached the USSR and, without declaring war, terminated the peace treaty. Thus, they attacked the USSR, which was not ready for war. Hitler was president of the Nazis, and Stalin of the USSR.
Chapter Five "Nazi Germany's Plan for an Advance Deep into the Country"
The basis for the offensive was the "Barbarossa" plan. It was approved by Directive No. 21 of the Supreme Command of the Wehrmacht, signed by Hitler, in December 1940. The idea was to inflict a crushing defeat on the Red Army and capture the USSR in a few months, using blitzkrieg (lightning war) tactics. Three army groups were formed for the attack:
"North" - the task was to defeat Soviet troops in the Baltics, capture Leningrad and the ports on the Baltic Sea (Tallinn, Kronstadt).
"Center" - the main attack on the Moscow direction (the Minsk-Smolensk-Moscow line). From Smolensk, the plan was to turn tanks north to join forces with the "North" group in capturing the Baltics and Leningrad, and then move on to Moscow. "South" would attack Moldova, Ukraine, Crimea, and advance to the Caucasus. Not only German troops but also allied forces from Romania, Finland, Hungary, Slovakia, and Italy, as well as volunteer units from other European countries, participated in the offensive.
Chapter Six, "The Failure of Germany's Plan"
The offensive began on June 22, 1941. In the first months, German troops actually advanced successfully. Group North came close to Leningrad, but was unable to take it.
Group Center, after heavy fighting, reached Moscow - the offensive on the capital began in September 1941. However, in December, Soviet troops launched a counteroffensive, and the Germans were pushed back. In the southern direction, Group South managed to occupy Ukraine, reach the Volga, and advance into the Caucasus. But the plan failed; the Germans did not know that the USSR was much stronger.