Eustace IV, Count of Boulogne Eustace IV, Count of Boulogne Eustace IV (c. 1127–1135 – 17 August 1153), Count of Boulogne, 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. Upon his mother's death in 1152 he inherited the county of Boulogne and other estates. Eustace was first mentioned in one of his parents' charters dated no later than August 1131. As heir to the English throne in 1137, he did homage for Normandy to Louis VII of
Battle of the Standard and in the settling of regained territory, he had drawn on the talent and resources of the Anglo-Norman lands. The death of Henry I in 1135, weakening England, made David more reliant on his native subjects, and allowed him to contemplate winning control over substantial areas of northern England. Henry I had wished his inheritance to pass to his daughter Matilda, and in 1127 made his notables swear an oath to uphold the succession of Matilda (David was the first layman to do so). Many of the English and Norman magnates and barons were against Matilda because she was married