After John's failed attempt to reconquer Normandy, the baron had his last straw. John learned of a coup and did everything he could to stop it, from buying time to gain papal support, to declaring himself a crusader in the hope of gaining political protection. None of this worked and the Baron's "Army of God" marched on London, conquering the cities as they advanced. John was forced to negotiate peace talks, as many of his royalists left to join the barons. In June 1215, without John's knowledge, he and the rebel leaders drew up the framework for the English constitution, the Magna Carta. This proclamation attempted to resolve the baron's problems with John, as well as address issues regarding ecclesiastical law and men's rights. Neither group intended to adhere to the terms of this potential peace, as Innocent III excommunicated the barons, resulting in a war to break the barons.