Today in the Middle Ages: May 21, 1420

On May 21, 1420, the Treaty of Troyes was concluded between England and France. Its terms included Henry V of England's betrothal to Catherine de Valois of France.

After his seemingly miraculous victory at Agincourt, Henry attempted to use the treaty to end the Hundred Years' War in his favor. It made him "heir to France" and disinherited the French Dauphin. But when Joan of Arc succeeded in placing the Dauphin on the French throne, he repudiated the treaty and continued the war.

Subsequently, Henry VI of England's mixed English and French descent and his accession to the thrones of both nations in early infancy further destabilized the situation and prepared the ground for the Wars of the Roses. Way to nation-build, Hal.