John Lackland (King John)
Upon the death of Richard the Lionheart in 1199, John Lackland ascended to the English throne becoming King John. Philippe II immediately again made incursions into Normandy. He further offended John by declaring that Arthur, John's nephew, was duke of Brittany and Normandy.
Isabelle of Angoulême
As a result of the declaration of John's marriage to Isabelle, on 30th August 1200 John Lackland demanded and married Hugues IX's (alias 'le Brun') fiancée Isabelle of Angoulême, possibly to prevent the union of the powerful Lusignan and Taillefer families. King John then rejected a summons to appear (as Duke of Aquitaine) before King Philippe II, technically his suzerain. In 1202, John was declared 'a felon' and Philippe II seized Anjou, Brittany, Maine, Normandy and Touraine.
John Lackland struck back with a surprise raid into Poitou where his mother, Eleanor, was being held as a hostage by Arthur, Duke of Brittany. John was able to capture not only Arthur, but Geoffrey and Hugues de Lusignan. This bold move threw Philippe II's offensive in the north off balance, and he had to temporarily halt his conquest of Normandy. However Arthur's mysterious death in April 1203 led many Breton lords and others to suspect John Lackland of murdering his nephew. The incident seriously undermined John Lackland ability to enlist support of the French barons. John Lackland departed from northern France in December 1203.
King John's mother, Eleanor, died in April 1204. Her domain was now threatened by a casual French offensive. Consequently in 1206, King John launched a campaign to secure the lands of his mother, Eleanor of Aquitaine, in southwest France.
Philippe II and John Lackland agreed to a truce on 26 October 1206. The French king held Anjou, Brittany and Maine, as well as Normandy. This was essentially the basic 'Angevin' claims of the Platagenet line, less Aquitaine. Except for brief periods of English occupation during the later Hundred Years' War, Anjou and Normandy were lost to the the Platagenet kings of England.