Coucy was made earl in 1080 and, probably that same year, resigned his position and returned to Normandy, losing all of the lands that he held in England.
Robert de Mowbray raised an army and attacked the Scots taking them by surprise on 13 November (St Brice's Day).
Earlier that same year, Geoffrey de Montbray died and Mowbray succeeded to his uncle's large estates, becoming one of the most powerful barons in the kingdom.
[1] Mowbray married in 1095 to Matilda, daughter of Richer de l'Aigle, and niece of Hugh d'Avranches, 1st Earl of Chester.
The merchants who owned the vessels complained to the king and Mowbray was commanded to attend the Curia Regis to explain his actions.
[1] As a result of his part in the rebellion Mowbray forfeited his estates and was imprisoned for life, initially at Windsor Castle.
Orderic Vitalis gives the following description of Robert de Mowbray: "Powerful, rich, bold, fierce in war, haughty, he despised his equals and, swollen with vanity, disdained to obey his superiors.