Some slight check, too, was retained upon the crown owing to a series of disputed successions to the throne. The Anglo-Saxon monarchy had always been in theory elective, and William had been careful to observe the form. His son, William II, had to obtain election in order to secure the throne against the claims of his elder brother Robert, and Henry I followed his example for similar reasons. Each had to make election promises in the form of a charter; and election promises, although they were seldom kept, had some value as reminders to kings of their duties and theoretical dependence upon the electors. Gradually, too, the kings began to look for support outside their Norman baronage, and to realize that even the submerged English might serve as a makeweight in a balance of opposing forces. Henry I bid for London's support by the grant of a notable charter; for, assisted by the order and communications with the Continent fostered by Norman rule, commerce was beginning to flourish and towns to grow. London was already distancing Winchester in their common ambition to be the capital of the kingdom, and the support of it and of other towns began to be worth buying by grants of local government, more especially as their encouragement provided another check on feudal magnates. Henry, too, made a great appeal to English sentiment by marrying Matilda, the granddaughter of Edmund Ironside, and by revenging the battle of Hastings through a conquest of Normandy from his brother Robert, effected partly by English troops.