When Napoleon invaded Russia in 1812, he assembled a force of over 600,000 men supported by roughly 200,000 horses. While popular history attributes the destruction of the Grande Armée to the freezing cold, the logistical nightmare began during the heat of summer due to equine nutrition. European warhorses were accustomed to a rich diet of dry grain and oats, which provided the dense calories needed to pull heavy supply wagons and carry armored cavalry.
As the French advanced, Russian scorched-earth tactics destroyed granaries, leaving the army unable to secure oat fodder. Desperate handlers turned to feeding their horses damp, green meadow grass and green rye. This abrupt dietary change was catastrophic.
Thousands of horses suffered from severe colic, dysentery, and bloating. Combined with exhaustion and heat, thousands of horses dropped dead daily along the dusty Russian roads long before reaching Moscow. By the time Napoleon entered the empty city, he had already lost over half of his livestock.
Without horses to pull the supply trains, food, medical equipment, and ammunition wagons were abandoned across hundreds of miles. When the retreat finally began, the lack of draft animals meant the supply chain could not move, stranding supplies and turning a structured retreat into a chaotic death march where starving soldiers were forced to eat the remaining draft animals.