In 1111 Robert II died, and Charles' cousin Baldwin VII became count. Charles was a close advisor to the new count (who was several years younger), who around 1118 arranged Charles' marriage to the heiress of the count of Amiens, Margaret of Clermont. The childless count Baldwin was wounded fighting for the king of France in September 1118, and he designated Charles as his successor before he died in July 1119.
Charles was noted for his kindness and generosity towards the poor, and during a time of famine he distributed bread to them. He also took action to prevent grain from being hoarded and sold at excessively high prices. Some of those engaged in that activity then conspired to kill Charles, which they accomplished at the Church of St. Donatian in Bruges. The murder of the popular Charles provoked a great deal of outrage, and he was soon regarded as a martyr and saint. He was beatified in 1884.
The Erembalden, a powerful family in Bruges who had murdered Charles, were arrested and executed by the angered people of Bruges and Ghent. The French king Louis VI, who had supported the revolt against the Erembalden, used his power to enforce his candidate, William Clito on the Flemish throne.