During the period when Francis was living in Gubbio, a fierce wolf appeared in the country and began attacking livestock. Soon the wolf graduated to direct assaults on humans, and not long after began to dine upon them exclusively. It was known for lingering outside of the city gates in wait for anyone foolish enough to venture beyond them alone. No weapon was capable of inflicting injury upon the wolf, and all who attempted to destroy it were devoured. Eventually mere sight of the animal caused the entire city to raise alarm and the public refused to go outside the walls for any reason. It was at this point, when Gubbio was under siege, that Francis announced he was going to take leave and meet the wolf. He was advised against this more than once but, irrespective of the warnings, made the sign of the Cross and went beyond the gates with a small group of followers in tow. When he neared the lair of the wolf the crowd held back at a safe distance, but remained close enough to witness what transpired.
The wolf, having seen the group approach, rushed at Francis with its jaws open. Again Francis made the sign of the Cross and commanded the wolf to cease its attacks in the name of God, whereupon the wolf trotted up to him docilely and laid at his feet, putting its head in his hands. The Fioretti then describes word-for-word his dealings with the wolf:
"Brother wolf, thou hast done much evil in this land, destroying and killing the creatures of God without his permission; yea, not animals only hast thou destroyed, but thou hast even dared to devour men, made after the image of God; for which thing thou art worthy of being hanged like a robber and a murderer. All men cry out against thee, the dogs pursue thee, and all the inhabitants of this city are thy enemies; but I will make peace between them and thee, O brother wolf, is so be thou no more offend them, and they shall forgive thee all thy past offences, and neither men nor dogs shall pursue thee any more."
The wolf bowed its head and submitted to Francis, completely at his mercy.
"As thou art willing to make this peace, I promise thee that thou shalt be fed every day by the inhabitants of this land so long as thou shalt live among them; thou shalt no longer suffer hunger, as it is hunger which has made thee do so much evil; but if I obtain all this for thee, thou must promise, on thy side, never again to attack any animal or any human being; dost thou make this promise?"
In agreement the wolf placed one of its forepaws in Francis' outstretched hand, and the oath was made. Francis then commanded the wolf to return with him to Gubbio. Meanwhile the townsfolk, having heard of the miracle, gathered in the city marketplace to await Francis and his companion, and were shocked to see the ferocious wolf behaving as though his pet. When Francis reached the marketplace he offered the assembled crowd an impromptu sermon with the tame wolf at his feet. He is quoted as saying: "How much we ought to dread the jaws of hell, if the jaws of so small an animal as a wolf can make a whole city tremble through fear?" With the sermon ended Francis renewed his pact with the wolf publicly, assuring it that the people of Gubbio would feed it from their very doors if it ceased its depredations. Once more the wolf placed its paw in Francis' hand.
Thereafter Gubbio venerated Francis and he received great praise from its citizens. Many of them were convinced by the miracle and offered their thanks to God, going on to be converted. This episode in the Fioretti is concluded with a note that the wolf lived for a further two years at Gubbio, going from home to home for sustenance and honoring the provisions of its agreement with Francis. At its death the city was saddened, for even though it had slain so many it was a symbol of the sanctity of Francis and the power of God.