Editing 1203 (section)

==== Europe ====
* Spring &ndash; King [[Philip II of France]] invades [[Duchy of Normandy|Normandy]] and attacks a number of castles in the surrounding region. In April, [[John, King of England]] loses the support of his French vassals who desert him. Philip enters [[Rouen]], leading to the eventual [[Treaty of Paris (1259)]] and unification of Normandy and France.
* At Rouen, [[William de Braose, 4th Lord of Bramber|William de Braose]], an English nobleman, becomes the guardian of the imprisoned 16-year-old [[Arthur I, Duke of Brittany|Arthur of Brittany]], designated heir to the throne of [[Kingdom of England|England]] – who is not known to be alive after April and is probably murdered by or at the orders of his uncle, King John.
* August &ndash; [[Siege of Château Gaillard]]: French forces under Philip II begin the siege at [[Château Gaillard]] as part of a campaign to reconquer the continental properties of King John of England. During the winter of 1203/1204, the English under [[William Marshal, 1st Earl of Pembroke|William Marshal]] attempt to relieve the castle.
* October &ndash; [[Brothers' Quarrel (Hungary)|Brothers' Quarrel]]: [[Emeric, King of Hungary]] captures his rebellious brother [[Andrew II of Hungary|Duke Andrew]] without resistance following their third confrontation in recent years.<ref>{{cite book |last=Engel |first=Pál |year=2001 |title=The Realm of St Stephen: A History of Medieval Hungary, 895–1526 |pages=86–87 |publisher= I.B. Tauris Publishers |isbn=1-86064-061-3}}</ref>
* [[December 6]] &ndash; King John abandons the lands that have been held by the [[Duke of Normandy|Dukes of Normandy]] for over a hundred years and returns to England. Only two castles hold out against the French forces – they are [[Château de Chinon|Chinon Castle]], controlled by [[Hubert de Burgh, 1st Earl of Kent|Hubert de Burgh]] and [[Château de Loches|Loches Castle]].
* The [[Oeselians]] ravage [[Denmark|Danish Scania]]. The returning pirates later skirmish with the German settlers of [[Riga]], near [[Visby]] in [[Gotland]].