With all these factors combined to create a deeply unpopular monarch, the barons called for constitutional reform. Instead of forming armies to help the king return to Normandy, as he demanded, the barons acted collectively and marched to London, where their numbers were inflated by disgruntled merchants. As the barons were in control of London and some of them even renounced their oath of allegiance to the king and instead supported the nobleman Robert Fitzwalter (1162-1235), John had no choice but to give in to their demands. Thus, the barons forced the king to sign the Magna Carta in 1215, on which was based a constitution that limited the power of the monarch and protected the rights of the barons. In addition, medieval affairs concerned the clauses of the Magna Carta, which dealt with specific issues such as guardianship and dowry, debt collection, and maintaining the freedom of navigation of rivers. [145] Even in the 13th century, certain clauses of the Magna Carta rarely appeared in legal cases, either because the issues in question were no longer relevant or because the Magna Carta had been replaced by more relevant legislation.