John was acknowledged as king in England and Normandy, Aquitaine was secured for him by its duchess, his mother Eleanor; but Anjou, Maine, and Touraine did homage to Arthur, the son of his elder brother Geoffry, the late Duke of Britanny.
The ambition of Philip, who protected his cause, turned the day against Arthur; the Angevins rose against the French garrisons with which the French king practically annexed the country, and in May 1200 a treaty between the two kings left John master of the whole dominion of his house.

But fresh troubles broke out in Poitou; Philip, on John's refusal to answer the charges of the Poitevin barons at his Court, declared in 1202 his fiefs forfeited; and Arthur, now a boy of fifteen, strove to seize Eleanor in the castle of Mirebeau.

Surprised at its siege by a rapid march of the king, the boy was taken prisoner to Rouen, and murdered there in the spring of 1203, as men believed, by his uncle's hand.

This brutal outrage at once roused the French provinces in revolt, while Philip sentenced John to forfeiture as a murderer, and marched straight on Normandy.

The ease with which the conquest of the Duchy was effected can only be explained by the utter absence of any popular resistance on the part of the Normans themselves.