[The Search for Martrydom] was the ultimate idea in the remarkable business of his expedition among the Saracens in Syria…His idea, of course, was to bring the Crusades in a double sense to their end; that is, to reach their conclusion and to achieve their purpose. Only he wished to do it by conversion and not by conquest; that is, by intellectual and not material means…It was, of course, simply that it was better to create Christians than to destroy Moslems…It was not absurd to suppose that this might be effected, without military force, by missionaries who were also martyrs. The Church had conquered Europe in that way and may yet conquer Africa and Asia in that way. But there was still another sense in which he was thinking of martyrdom not as a means to end but as an end in itself; in the sense that to him the supreme end was to come closer to the example of Christ.

…He made a dash for his Mediterranean enterprise something like a schoolboy running away to sea. In the first act of that attempt, he characteristically distinguished himself by becoming the Patron Saint of Stowaways.  He never thought of waiting for introductions or bargains or any of the considerable backing that he already had from rich and responsible people. He simply saw a boat and threw himself into it, as he threw himself into everything else.

…He arrived at the headquarters of the Crusade which was in front of the besieged city of Damietta, and went on in his rapid and solitary fashion to seek the headquarters of the Saracens. He succeeded in obtaining an interview with the Sultan; and it was at that interview that he evidently offered, and as some say proceeded, to fling himself into the fire, as a divine ordeal, defying the Moslem religious teachers to do the same. It is quite certain that he would have done so at a moment’s notice. Indeed, throwing himself into the fire was hardly more desperate, in any case, than throwing himself among the weapons and tools of torture of a horde of fanatical Mahomedans and asking them to renounce Mahomet. It is further said that Mahomedan muftis showed some coldness toward the proposed competition, and that one of them quietly withdrew while it was under discussion, which would also appear credible. There may be something in the story of the individual impression produced on the Sultan, which the narrator represents as a sort of secret conversion. There may be something in the suggestion that the holy man was unconsciously protected among half-barbarous orientals by the halo of sanctity that is supposed in such places to surround an idiot. There is probably as much or more in the more generous explanation of that graceful though capricious courtesy and compassion which mingled with wilder things in the stately Soldans of the type and tradition of Saladin. Finally, there is perhaps something in the suggestion that the tale of Saint Francis might be told as a sort of ironic tragedy and comedy called The Man Who Could Not Get Killed. Men liked him too much for himself to let him die for his faith; and the man was received instead of the message. But all these are only converging guesses at a great effort that is hard to judge because it broke off short like the beginning of a great bridge that might have united East and West, and remains one of the great might-have-beens of history.

Collected Works of G.K. Chesterton, Volume II, Saint Francis of Assisi