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 V, Count Palatine of the Rhine first he supported him, but switched sides to Philip of Swabia in 1203. Having divided the Welf allodial lands with his brothers Otto and William of Winchester, Henry then ruled over the northern Saxon territories around Stade and Altencelle and also was confirmed as count palatine by King Philip. When the German throne quarrel ended with Philip's assassination in 1208, Henry again sided with Otto IV. In Imperial service, he tried to ward off the territorial claims by the Rhenish Prince-archbishops of Cologne, Trier and Mainz, though to no avail. After the death of his cousin Arthur I, Duke of