Eustace IV ruled the County of Boulogne from 1146 until his death. He was the eldest son of King Stephen of England and Countess Matilda I of Boulogne. When his father seized the English throne on Henry I's death in 1135, he became heir apparent to the English throne but predeceased his father.

Stephen, often referred to as Stephen of Blois, was King of England from 22 December 1135 to his death in 1154. He was Count of Boulogne jure uxoris from 1125 until 1147 and Duke of Normandy from 1135 until 1144. His reign was marked by the Anarchy, a civil war with his cousin and rival, the Empress Matilda, whose son, Henry II, succeeded Stephen as the first of the Angevin kings of England.