It is not improbable that Fitz-Walter's election as leader of the remonstrant barons was in some measure due to his official position in the city. It is also probable, as Mr. Riley has pointed out, that the unopposed admission of the barons into the city, on the 24th May, 1215, may have been facilitated by Fitz-Walter's connexion, as castellain, with the Priory of Holy Trinity, situate in the vicinity.
But there were other reasons for selecting Fitz-Walter as their leader at this juncture. If the story be true, Fitz-Walter had good reason to be bitterly hostile to King John, for having caused his fair daughter Maude or Matilda to be poisoned, after having unsuccessfully made an attempt upon her chastity.(188) This is not the only crime of the kind laid to the charge of this monarch,(189) and there appears to be too much reason for believing most of the charges against him to be true. It is certain that Fitz-Walter was one of the first to entertain designs against John, and that he and Eustace de Vesci, on whose family the king is said to have put a similar affront, were forced to escape to France. The story how Fitz-Walter attracted John's notice by his prowess at a tournament in which he was engaged on the side of the French, and was restored to the King's favour and his own estates, is familiar to all.
After a feeble attempt to capture Northampton, the barons, with Fitz-Walter at their head, accepted an invitation from the citizens of London to enter the city. They made their entry through Aldgate.(190)
The concession which John had recently made to the citizens, viz.:--the right of annually electing their own mayor(191)--had failed to secure their allegiance. The city became thenceforth the headquarters of the barons,(192) and the adhesion of the Londoners was followed by so great a defection from the King's party (including among others that of Henry de Cornhill), that he was left without any power of resistance.(193)
The citizens met their reward for fidelity to the barons when John was brought to bay at Runnymede. In drafting the articles of the Great Charter the barons, mindful of their trusty allies, made provision for the preservation of the city's liberties, and the names of Fitz-Walter and of the mayor of the city appear among those who were specially appointed to see that the terms of the charter were strictly carried out.(194)