Beginning in 1323 Charles was confronted with a peasant revolt in Flanders, and in 1324 he made an unsuccessful bid to be elected Holy Roman Emperor. As Duke of Guyenne, King Edward II of England was a vassal of Charles, but he was reluctant to pay homage to another king. In retaliation, Charles conquered the Duchy of Guyenne in a conflict known as the War of Saint-Sardos (1324). In a peace agreement, Edward II accepted to swear allegiance to Charles and to pay a fine. In exchange, Guyenne was returned to Edward but with a much-reduced territory.