Answer:
Geography and Harsh weather played a major role in Napoleon's defeat during his invasion of A) Russia.
Step-by-step explanation:
When Napoleon decided to march against Russia, the context was the following. First, Russia and Great Britain had trade routes and agreements, Napoleon saw both of them as enemies and he decided to seize, guard and break the trade routes. In the second place, he used the fact that Poland was under Russian dominion to declare that his excursion against Russia was to liberate the polish. However, he wanted to conquer Russia.
Now, he managed to win polish territory from Russia and pushed all the through its borders conquering Moscow. Where he stayed demanding Russian Surrender, however, the Russians didn't do it, because they had strong positions in other parts of his country. Now by this point, french troops were tired o war because they had been fighting a couple of months in harsh conditions very different from the ones they were accustomed to.
So, the Russians used guerrilla strategies to fight them and when Napoleon decided to leave Moscow he lost the war. Because he tried to attack Russian cities until they surrendered, but Napoleon found a wall in "Kaluga" and he decided to retreat, in their run french soldiers suffered the worst of the guerrilla attacks, weather and harsh environment weakening to its ultimate point and Russians rushed them to defeat them. But the Russians never stopped, until they expelled all Frenchs from their territory. Also, Napoleon had to gather more troops because he feared an attack in his capital city "Paris".