The 100 years War was a war between England and France, over the control of France. It wasn't really one long war, but lots of them that kept getting resolved and broken by treaties.
After the war had gone on for awhile there was a French girl named Joan who saw visions from God, she listened to these visions and went to talk to the king.
At first he didn't really listen to her, but he eventually believed her. Soon he gave her control of the whole army.
At first everyone was reluctant to follow her, but seeing the positive results her command had, they quickly adjusted and did what she said.
Joan was wounded in battle and captured by the enemy, who convicted her of witchcraft and had her burned at the stake
After her death, the Duke of Burgundy, switched sides and helped French cause. Internal struggles related to which dynasty would assume control further weakened England. Taking advantage of these situations, French troops were able to drive the English out of France , and win the war. The French also used new weapons, like the cannon, to help them win. This began a new age of warfare.