Why was Napoleons Russian campaign such a disaster

A large number of French soldiers froze to death in the winter of 1812 within a matter of weeks of their emperor Napoleon Bonaparte leading them into Russia. The loss of manpower was one of the principal reasons why Napoleon withdrew from the outskirts of Moscow, and hence lost his Russian campaign. 

But why was so ruthless a general and so obsessively careful a tactician as Napoleon foolhardy enough to lead an unprepared army into the frozen wastes of Russia In fact, he thought he was prepared, and his troops were originally well clothed with thick winter coats. The only problem was that, so the story goes, he chose at the last moment to replace the brass of the soldiers buttons with tin, to save money. 

Metallic tin has many allotropic forms rhombic white tin (also called /3-tin) is stable at temperatures above 13 °C, whereas the stable form at lower temperatures is cubic grey tin (also called a-tin). A transition such as tin(white) tin ey) is called a solid-state phase transition. 

The air temperature when Napoleon entered Russia was apparently as low as —35 °C, so the soldiers tin buttons converted from white to grey tin and, concurrently, disintegrated into powder. So, if this story is true, then Napoleon s troops froze to death because they lacked effective coat fastenings. Other common metals, such 

The transition from white tin to grey was first noted in Europe during the Middle Ages, e.g. as the pipes of cathedral organs disintegrated, but the process was thought to be the work of the devil. 

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