From the 850s, Angers suffered from its situation on the border with Brittany and Normandy. In September 851, Charles the Bald and Erispoe, a Breton chief, met in the town to sign the Treaty of Angers, which secured Breton independence and fixed the borders of Brittany. However, the situation remained dangerous for Angers, and Charles the Bald created in 853 a wide buffer zone around Brittany comprising parts of Anjou, Touraine, Maine and Sées, which was ruled by Robert the Strong, a great-grandfather of Hugh Capet.