Russian Winter, sometimes personified as "General Frost" or "General Winter", is an aspect of the climate of Russia that has contributed to military failures of several invasions of Russia. Mud is a related contributing factor that impairs military maneuvering in Russia and elsewhere, and is sometimes personified as "General Mud". Russians call those muddy conditions rasputitsa, which occur with autumnal rains and spring thaws in Russia and make transport over unimproved roads difficult. Winter as a contributing factor to military defeat In his study of winter warfare in Russia, author Allen F. Chew concludes that "General Winter" was a 'substantial contributing factor'—not a decisive one—in the military failures of both Napoleon's and Hitler's invasions of Russia. He notes that Napoleon's army was already suffering significant attrition before winter, owing to lack of supplies, disease, desertions and casualties of war. Likewise, Hitler's Wehrmacht had already suffered 734,000 casualties and was running low on supplies in November 1941, before the arrival of winter. Examples Swedish invasion of 1708 In the Great Northern War, Charles XII of Sweden invaded Russia in 1707. The Russians retreated, adopting a scorched-earth policy. This winter was the most brutal of the 18th century, so severe that the seaport of Venice froze during the Great Frost of 1709. Charles' 35,000 troops were crippled, and by spring only 19,000 were left. The Battle of Poltava in late June 1709 sealed the end of the Swedish Empire. French invasion of 1812 Napoleon's Grande Armée of 610,000 men invaded Russia, heading towards Moscow, in the beginning of summer on 24 June 1812. The Russian army retreated before the French and again burnt their crops and villages, denying the enemy their use. Napoleon's army was ultimately reduced to 100,000. His army suffered further, even more disastrous losses on the retreat from Moscow, which started in October. Multiple sources concur that winter and its aftermath was only a contributing factor to Napoleon's defeat and retreat. To counter claims that the French defeat resulted from winter weather, Denis Davydov published a military historical analysis, titled "Was it Frost that Devastated the French Army in 1812?", wherein he demonstrated that the French suffered casualties in battles during relatively mild weather and outlined multiple causes for their defeat. He drew on both his direct observations and on those of foreign commentators, including French authors. According to Chew in 1981, the main body of Napoleon's Grande Armée,