In what ways was the German attack on the Soviet Union different from earlier invasions of other nations?

It is regarded as one of the most significant military operations in modern warfare history, involving Germany and its allies using more than 3,000,000 troops for the attack.

Explanation:

The German attack on the Soviet Union is different from earlier invasions of other nations due to the following reasons:

1. It involves the biggest troops never seen before. Estimating to more than 3,000,000 soldiers.

2. It is considered as the significant turning point in the World War II

3 It led to the earliest defeat of the German soldiers in the World War II

4. The German invasion never considered that the attack would last for months reaching the winter period.

5. The Soviets were more resilient than the Germans had planned.

the answer is a) high entry costs