Arthur I, Duke of Brittany, grandson of King Henry II of England (died 1203)

Arthur I was 4th Earl of Richmond and Duke of Brittany between 1196 and 1203. He was the posthumous son of Geoffrey II, Duke of Brittany, and Constance, Duchess of Brittany. Through Geoffrey, Arthur was the grandson of King Henry II of England and Duchess Eleanor of Aquitaine, and the nephew of King Richard I of England.

Henry II was King of England from 1154 until his death in 1189. During his reign he controlled England, substantial parts of Wales and Ireland, and much of France, an area that was later called the Angevin Empire, and also held power over Scotland for a time and the Duchy of Brittany.

March 29 is the 88th day of the year in the Gregorian calendar; 277 days remain until the end of the year.