200 years ago, Napoleon’s army took on the Russians in the Battle of Maloyaroslavets. Though a French victory, the battle marked a major strategic setback, as the Russians moved to block Napoleon’s path of retreat out of their country. In the end, only 10,000 Frenchmen out of an initial half a million made it out of Russia alive.

Why did this happen? Historians still puzzle over this military catastrophe today, Big Think reports, but a new theory points to an unlikely culprit: the army’s buttons.

Ainissa Ramirez, a materials scientist at Yale University, explains that the bonding structure of tin atoms begins to change when temperatures drop below 56°F, and tin was the major metal used to make buttons in the French army’s uniforms. As the severe Russian temperatures approached -30°C, the buttons may have turned to dust.

In other words, the harsh Russian winter, combined with the chemical properties of tin, may have led to “the greatest wardrobe malfunction in history.”

Here, Ramirez explains the unfortunate gaff, plus some fun facts about tin:

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