I just want to clarify a couple of potential misconceptions. Hitler invaded Russia (the USSR) in June. That is probably the optimal time to invade it. It is after the period of "Rasputitsa" or mud season that occurs in the spring when rain and melting snow makes unpaved roads difficult to traverse. However June isn't quite winter. Hitler thought that he had a solid 3-4 month period before the cold set in to destroy the majority of the Red Army and capture vital cities like Leningrad and Moscow. He came very close to that goal but ultimately he underestimated the size and the resiliency of the Soviet Union and its armed forces.

The entire German war plan rested on a quick campaign (the German term blitzkrieg literally means lightning war) which turned out to be overly optimistic. So the miscalculation wasn't that Hitler attacked at the wrong time of the year or that he didn't anticipate the Russian winter - it is that he fundamentally underestimated Russian capabilities and believed that victory could be achieved faster than was possible.

Now, Napoleon. Napoleon also invaded Russia in, unsurprisingly, June. Napoleon's plan wasn't one of conquest - he knew that Russia was too big for that. He simply wanted the Russian Tsar to agree to his terms in a peace treaty. To that end, he simply intended to draw the Russian army into a pitched battle and destroy it. After that, the Tsar would have little choice. Again, Napoleon never planned to go too deeply into Russian territory. However as he invaded, the Russians simply refused to fight him. All of his traps and attempts to goad the Russian army into a large battle were fruitless. The Russian army simply retreated farther and farther back.

By around August, Napoleon had a few choices about what to do. He could give up his invasion and leave Russia. He could set up winter quarters in Western Russia where he had plenty of supplies and his army could be well provisioned, and then continue his war in the spring. Napoleon chose the third option, which was to continue on eastward to Moscow. Napoleon believed that the Russians couldn't surrender Moscow without battle, and that upon beating them and capturing the city, his war would be won. However this was a very risky strategy since his army would very deep into Russia and too far away from his supplies to be able to stay there for winter. Napoleon was confident that it wouldn't come to that - he would beat the Russians before winter.

However he was wrong. While the Russians did give him a battle he was looking for, the outcome was rather inconclusive. Napoleon didn't get the resounding victory he sought. Napoleon did capture Moscow in September. However again, that wasn't enough to get the Tsar to negotiate. Napoleon was simply unable to end the war. He knew he didn't have the supplies to stay in Moscow in the winter, he ordered a retreat, which ended up being a disaster.

However the key things to take away from this was that Napoleon, like Hitler, intended to defeat Russia well before the onset of winter. In fact, most of the campaign took place in the summer and early fall, and by early winter, the French army was out of Russia.

Who else invaded Russia? The Mongols invaded Russia in winter quite successfully in the 13th century. If anything, the winter aided them. The mongols and their horses were used to winter cold plus cold weather helped turn frozen rivers into highways. The Russians tended to campaign in the spring and summer and were unprepared for the Mongol invasion.

The Poles invaded in beginning of the 17th century. However I haven't seen any evidence of winter being a much of a factor. The Poles captured Moscow but were eventually driven out.

Finally there were the Swedes who invaded western Russia/Ukraine in 18th century. The Russians were quite successful in drawing the Swedes deeper into their territory and attacking Swedish supply lines instead of engaging the Swedish army directly. It is hard to say how much winter was a factor, however the logistics situation strongly favored the Russians, which was the deciding factor.

its not that they "attack during winter". its that wars and campaigns last a long time aka more then one year which means winter fighting. Russia is known for its harsh winters and its a logistical nightmare.

The myth of Hitler being hindered only the winter was invented by his generals. The last thing stopping German advances was winter. The Germans were also there for several years, including several non winters. They were defeated by the same things that defeat most armies--strategic skill and better industrial backing. The Russians actually were what defeated Hitler, not "General Winter" of Company of Heroes fame.