When the English reached Rouen, the walls were defended with 60 towers, each containing three cannons and 6 gates protected by barbicans. The garrison of Rouen had been reinforced by 4,000 men and there were some 16,000 civilians willing to endure a siege. The defence was lined by an army of crossbow men under the command of Alain Blanchard, commander of the crossbows (arbalétriers), and second in command to Guy le Bouteiller, a Burgundian captain and the overall commander. To besiege the city, Henry decided to set up four fortified camps and barricade the River Seine with iron chains, completely surrounding the city, with the English intending to starve out the defenders. The duke of Burgundy, John the Fearless, had captured Paris but did not make an attempt to save Rouen and advised citizens to look after themselves. By December, the inhabitants were eating cats, dogs, horses, and even mice. The streets were filled with starving citizens. Despite several sorties led by the French garrison, this state of affairs continued. The French surrendered on 19 January. Henry went on to take all of Normandy, apart from Mont-Saint-Michel, which withstood blockade. Rouen became the main English base in northern France, allowing Henry to launch campaigns on Paris and further south into the country.