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
Ranuccio I Farnese, Duke of Parma however, manage to engineer a match with Margherita de' Medici, daughter of Cosimo II of Tuscany. The husband of Margherita Aldobrandini, niece of Pope Clement VIII, Ranuccio, the son of a Portuguese infanta, was considered as a potential king of Portugal when his childless great-uncle King Henry I died. The throne, however, passed to Philip II of Spain, whose troops had promptly occupied the country after Henry I's death. His great-uncle Henry I of Portugal's death triggered the struggle for the throne of Portugal when Ranuccio was 11 years old. As the son of the late elder daughter of Infante