Answers:
Russia’s scorched-earth policy; the harsh Russian winter.
Step-by-step explanation:
As Napoleon´s troops advanced into deeper Russian territory in the year 1812, the Russians deployed a military strategy called scorched earth policy which entails that the retreating troops burn down any kind of resource, like water, food, industrial materials, etc., so that the advancing troops cannot take advantage of these resources. This, along with the harsh Russian winter were notably the two factors that played the biggest role in the defeat of the French.