dynamic) friction occurs when the ski is moving over the snow. Warfare Snow affects warfare conducted in winter, alpine environments or at high latitudes. The main factors are impaired visibility for acquiring targets during falling snow, enhanced visibility of targets against snowy backgrounds for targeting, and mobility for both mechanized and infantry troops. Snowfall can severely inhibit the logistics of supplying troops, as well. Snow can also provide cover and fortification against small-arms fire. Noted winter warfare campaigns where snow and other factors affected the operations include: The French invasion of Russia, where poor traction conditions for ill-shod horses made it difficult for supply wagons to keep up with troops. That campaign was also strongly affected by cold, whereby the retreating army reached Neman River in December 1812 with only 10,000 of the 420,000 that had set out to invade Russia in June of the same year. The Winter War, an attempt by the Soviet Union to take territory in Finland in late 1939 demonstrated superior winter tactics of the Finnish Army, regarding over-snow mobility, camouflage, and use of the terrain. The Battle of the Bulge, a German counteroffensive during World War II, starting December 16, 1944, was marked by heavy snowstorms that hampered allied air support for ground troops, but also impaired German attempts to supply their front lines. On the Eastern Front with the Nazi invasion of Russia in 1941, Operation Barbarossa, both Russian and German soldiers had to endure terrible conditions during the Russian winter. While use of ski infantry was common in the Red Army, Germany formed only one division for movement on skis. The Korean War which lasted from June 25, 1950, until an armistice on July 27, 1953, began when North Korea invaded South Korea. Much of the fighting occurred during winter conditions, involving snow, notably during the Battle of Chosin Reservoir, which was a stark example of cold affecting military operations, especially vehicles and weapons. Effects on plants and animals Plants and animals endemic to snowbound areas develop ways to adapt. Among the adaptive mechanisms for plants are freeze-adaptive chemistry, dormancy, seasonal dieback, survival of seeds; and for animals are hibernation, insulation, anti-freeze chemistry, storing food, drawing on reserves from within the body, and clustering for mutual heat. Snow interacts with vegetation in two principal ways, vegetation can influence the deposition and retention of snow and, conversely, the presence of snow can affect