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.[1]