Answer:
The winter in 41'-42'. Climate problems and weakening of the military.
Step-by-step explanation:
There were several natural events that caused problems for Hitler and the German military when they invaded the Soviet Union during World War II. One of the most significant was the harsh winter of 1941-1942, which severely hindered the German military's progress and contributed to the failure of the invasion. The German military was not prepared for the extreme cold, and many soldiers froze to death or suffered from frostbite. The winter also made it difficult for the Germans to transport supplies and equipment, which hindered their ability to maintain their advance. Additionally, the Soviet Union had a large and well-trained military, and the Red Army was able to effectively counter the German invasion and eventually push the Germans back.