Roi de France (1350-1364king of France (1350-64), the son of King Phillip VI. During his reign he debased the coinage to raise funds for the Hundred Years' War. John was captured in 1356 by Edward, the Black Prince, at the Battle of Poitiers and was imprisoned in England. His son Charles, later Charles V, acted as regent during his captivity. John was returned to France in 1360 to raise his ransom under the terms of the Peace of Brétigny. Because he was unsuccessful in collecting the 3 million crowns required, in 1364 John honorably resumed his captivity in England, where he died.