In 1048 Eustace joined his father-in-law's rebellion against the Emperor Henry III. The next year Eustace was excommunicated by Pope Leo IX for marrying within the prohibited degree of kinship. Eustace and Ida were both descended from Louis II of France, and just within the prohibited seventh degree. However, since not all their ancestors are known, there might have existed a closer relationship. The Pope's action was possibly at the behest of Henry III. The rebellion failed, and in 1049 Eustace and Godfrey submitted to Henry III. Eustace visited England in 1051, and was received with honour at the court of Edward the Confessor. Edward and Eustace were former brothers-in-law and remained political allies. On the other side of the political divide the dominant figure in England was Earl Godwin, who had recently married his son Tostig to the daughter of Eustace's rival the Count of Flanders. Furthermore, Godwin's son Sweyn Godwinson had been feuding with Eustace's stepson Ralph the Timid. A brawl in which Eustace and his servants became involved with the citizens of Dover led to a serious quarrel between the king and Godwin. The latter, to whose jurisdiction the men of Dover were subject, refused to punish them. His lack of respect to those in authority became the excuse for his being outlawed together with his family. They left England, but returned the next year in 1052 with a large army, aided by the Flemish. In 1052 William of Talou rebelled against his nephew Duke William of Normandy. Eustace could have been involved in this rebellion, although there is no specific evidence, for after William of Talou's surrender he fled to the Boulonnais court. The following years saw still further advances by Eustace's rivals and enemies. Count Baldwin of Flanders consolidated his hold over territories he had annexed to the east. In 1060 he became tutor of his nephew King Philip I of France. In contrast Eustace's stepson Walter of Mantes failed in his attempt to claim the County of Maine. He was captured by the Normans and died soon afterwards in mysterious circumstances.
These events evidently caused a shift in Eustace's political allegiances, for he then became an important participant in the Norman conquest of England in 1066. He fought at Hastings, although sources vary regarding the details of his conduct during the battle. The contemporary chronicler William of Poitiers wrote concerning him: The depiction in the Bayeux Tapestry shows a knight carrying a banner who rides up to Duke William and points excitedly with his finger towards the rear of the Norman advance. William turns his head and lifts up his visor to show his knights following him that he is still alive and determined to fight on. This conforms therefore with Eustace having somewhat lost his nerve and having urged the Duke to retreat while the Battle was at its height with the outcome still uncertain. Other sources suggest that Eustace was present with William at the Malfosse incident in the immediate aftermath of the battle, where a Saxon feigning death leapt up and attacked him, and was presumably cut down before he could reach William. Eustace received large land grants afterwards, which suggests he contributed in other ways as well, perhaps by providing ships.
Rebellion
In the following year, probably because he was dissatisfied with his share of the spoil, he assisted the Kentishmen in an attempt to seize Dover Castle. The conspiracy failed, and Eustace was sentenced to forfeit his English fiefs. Subsequently, he was reconciled to the Conqueror, who restored a portion of the confiscated lands.
Death
Eustace died circa 1087, and was succeeded by his son, Eustace III.
Marriage and progeny
Eustace married twice:
Firstly to Goda, daughter of the English king Æthelred the Unready, and sister of Edward the Confessor. Goda died circa 1047.
By his second wife, Eustace may also have had a daughter, Ida, wife of Conon, Count of Montaigu. Eustace also had a son, Geoffrey fitz Eustace, who married Beatrice de Mandeville, daughter of Geoffrey de Mandeville. Geoffrey and Beatrice were parents of William de Boulogne and grandparents of William's son Faramus de Boulogne.
