The first is that the Soviet Union is rich in land, many people have a thick industrial foundation, Germany can not eat a fat man will be beaten back, of course, can not ignore the British and American assistance to the Soviet Union such as the "Lend-Lease Act" and so on
The main indicator of success or failure of the second campaign was never to look at the number of tanks lost, the ratio of battle losses, etc., but to see whether its expected goals were achieved. A typical example is the Battle of Nomonhan, which although the Soviet Union invested a large number of heavy artillery, tanks, aircraft, etc., the casualty ratio was very ugly, the number of casualties basically reached 1:1, and the number of wounded even surpassed the Japanese army. More tanks were hung up than the number of tanks put in by the Japanese, and it was said that the Kwantung Army suffered a fiasco, and I think the Soviet Red Army actually won a crushing victory. But this battle had a profound impact on World War II, first of all, it showed muscles, whether it was the quality and quantity of tanks or the quality and quantity of artillery, it shocked the Japanese military northward faction, and told Japan that the Soviet Union was not easy to provoke; secondly, it seriously dealt a blow to Japan's military strength that was already poor at the beginning of the war, although the tanks were destroyed more than you, but my family was thick and your foundation was poor, and I died another 300 of them, and you would die another 200 countries that would go bankrupt; the most important thing was to thwart the ambition of the Japanese army to go north. It ensured the relative security of the Far East until Japan's surrender, and indirectly affected the trend of the entire World War II. So from a strategic point of view, although the results of Nomonhan were difficult to see, the strategic objectives were fully met, so both the Soviet Union and Japan agreed that this was a great victory for the Soviet Union.
The defeat of the Germans, a great siege of the city, the 872-day siege destroyed public facilities, water, energy and food supplies, resulting in an unprecedented famine in the Leningrad region, killing up to 1.5 million people and evacuating more than 1,400,000 civilians and soldiers, many of whom died of bombing and famine during the evacuation. The battle contained the German heavy army and the entire Finnish army. After the battle, a large number of Soviet troops were freed up for other strategic directions. It thwarted the German strategic objective of occupying Leningrad and held the powerful German Army Group North tightly on the northwestern Soviet battlefield, thus effectively supporting the Soviet victory in other battlefields.
Of course, some people artificially have the numerical superiority of technical equipment in the Soviet Army for 41 years, because the Soviet technical equipment, especially motorized vehicles, is lowly properly and poorly maintained (only 20% of the equipment can be put into battle immediately), the numerical advantage often exists only on paper, not on the battlefield, and most of the Soviet tanks and interceptors are produced in the mid-30s to 41 years The performance has become obsolete (rabbit clams waste military funds, and the Kiev fortification area built by rabbit clams is also a tofu slag project). In the end, although the Soviet Army was composed of the mechanized army unit, the formation was not reasonable, and the mixed formation of armored motorized equipment with different mobility capabilities led to the lack of mechanical power of the troops. As a result, even if the Soviets retreated, they still could not keep up with the German encirclement. Of course, the German army in 41 years was not a really mechanized force, the German army concentrated tanks and motorized vehicles to form a mobile unit to carry out deep encirclement, but these troops faced the vast combat area of the Eastern Front is very limited, and the Soviet besieged troops are often able to infiltrate back to the rear from the gap between the German encirclement after abandoning heavy equipment. Later in the war, when the Germans faced the Soviet encirclement, they found that even if heavy equipment and wounded people protruded from the gaps between the Soviet troops, they often just drilled into another encirclement, and finally these German breakthrough troops would gradually disintegrate, melt, and disappear like sugar cubes thrown into coffee.