Excerpts from Books and Wikipedia
"French King Phillip II Augustus, who laid siege to the city of Rouen in Normandy in mid-May 1204, was not a heroic figure. He bore little resemblance to the chivalrous ideal of military prowess and noble deeds. But he was a supremely intelligent ruler who thoroughly outwitted the Angevin kings of England. . . . When John's young nephew Arthur, a rival claimant to the English crown, was murdered at Rouen in April 1203, much of the French nobility in Angevin-ruled areas turned against him. . . .Philip invaded Normandy with 6,000 men and took the English fortress of Chateau-Gaillard after a long siege. The rest of Normandy succumbed without a fight. Rouen, however, had strong trading links with England. . . . After a forty-day siege, with no help from John forthcoming, Rouen surrendered on June 24." [1001 Days]