In an early strategic move, Henry came to the rescue of his very young nephew-in-law, the newly appointed Duke William of Normandy (who would go on to become William the Conqueror), to suppress a revolt by William's vassals. In 1047, Henry secured the dukedom for William in their decisive victory over the vassals at the Battle of Val-ès-Dunes near Caen; however, Henry would later support the barons against William until the former's death in 1060.