Baldwin V had a great deal of influence due in part to several marriages alliance between Flanders and England, France and Germany. He was close to his , Henry I,the king of France. From 1060 to 1067 Baldwin was the Regent for his nephew Philip I of France. In 1051 Baldwin had Richildis, the widow of Count Herman of Hainault, to marry his son Baldwin VI. This gave him control of Hainault through his son. This also led to a series of conflicts between Baldwin V and Emperor Henry III, as Hainault was part of the Holy Roman Empire. After a series of defeats Henry III withdrew back to Germany and died a short time later. In 1056 Baldwin received the whole of the Schelt march as a fief from Agnes of Poitou, regent for her son Henry IV, Holy Roman Emperor. Baldwin's daughter Matilda married William I of England, later king of England. At first the marriage was banned by Pope Leo IX. He did not give a reason but it was probably because the two were cousins. Some time between 1050 and 1052 the two married despite the ban. Although Baldwin allowed some Flemish support for his Norman conquest of England relations between Baldwin and his son-in-law William the Conqueror were not that friendly. The English king was wary of Baldwin's growing power. But by then Baldwin was growing old. He died 1 September 1067.