The Hundred Years' War

This was the middle of the Hundred Years' War, and France was losing badly. English forces controlled most of northern France, and the French heir, Charles VII, had not even been crowned. Into this chaos walked a teenage girl with zero military training and an impossible claim.

Joan arrived at Orleans in May 1429, and the English siege there collapsed in nine days. Historians still debate how much was tactical skill and how much was sheer morale — but either way, a nation that had forgotten how to win was suddenly remembering.