The young Charles of Orléans succeeded his father as duke and was placed in the custody of his father-in-law, the Count of Armagnac. Their faction became known as the "Armagnac" faction, and the opposing party led by the Duke of Burgundy was called the "Burgundian faction". Henry V of England took advantage of these internal divisions when he invaded the kingdom in 1415, winning a dramatic victory at Agincourt on 25 October and subsequently capturing many northern French towns. In 1418 Paris was taken by the Burgundians, who massacred the Count of Armagnac and about 2,500 of his followers. The future French king, Charles VII, assumed the title of Dauphin—the heir to the throne—at the age of fourteen, after all four of his older brothers had died in succession. His first significant official act was to conclude a peace treaty with the Duke of Burgundy in 1419. This ended in disaster when Armagnac partisans assassinated John the Fearless during a meeting under Charles's guarantee of protection. The new duke of Burgundy, Philip the Good, blamed Charles for the murder and entered into an alliance with the English. The allied forces conquered large sections of France.