Complex sentence: As soon as the annulment was granted Eleanor was engaged to Henry, Duke of Normandy, who became King Henry II of England in 1154 and was her third cousin (cousin of the third degree), nine years younger.
Split into simpler sentences: As soon as the annulment was granted, Eleanor became engaged to Henry, Duke of Normandy, who became King Henry II of England in 1154. Henry was her third cousin (cousin of the third degree), and nine years younger.