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
Henry I of France time of his death; for six years Henry's queen Anne of Kiev ruled as regent. At the time of his death, he was besieging Thimert, which had been occupied by the Normans since 1058. Henry I was betrothed to Matilda, the daughter of Conrad II, Holy Roman Emperor, but she died prematurely in 1034. Henry then married Matilda of Frisia, but she died in 1044, following a Caesarean section. Casting further afield in search of a third wife, Henry married Anne of Kiev on 19 May 1051. They had four children: Henry I of France Henry I (4 May 1008