Then John of Brienne himself landed in Europe to ask in person for the help that was so long in coming. He brought with him his beautiful daughter, Yolande, and her presence inspired the Pope with new hopes. He now proposed that the Emperor Frederick should marry the maiden and go forth to the Holy War as the heir of John of Brienne. The marriage took place in 1225, more than eleven years after Frederick's vow as a Crusader had first been taken. Almost immediately the Emperor showed his real motive in the marriage by declaring that as John held his royal rights only through his wife, they passed on her death to her daughter, through whom they were now held by her husband, and the Emperor therefore at once proclaimed himself "King of Jerusalem."

Not even then, after the unavailing opposition of John had died away, did Frederick start upon the Crusade. In his beautiful Sicilian kingdom, surrounded by learned Jews, cultivated Saracens, Norman troubadours and Italian poets, he had become too easy-going, too tolerant of all forms of faith or of none, to have any real religious motive to stimulate his actions. He was, indeed, inclined to meet even the Sultan of Egypt himself on terms of the friendliest equality.

But Honorius had been succeeded as Pope by the proud and domineering Gregory IX., to whom this spirit of dallying was loathsome. An imperative letter summoning the Emperor to fulfil his broken vow seemed at first to have some real effect, and in the August of 1227 a large army assembled at Brindisi. There the men were seized by fever, and though Frederick actually set sail with the fleet, it was only to return after three days to the harbour of Otranto, while the host dispersed. The Pope was furious, and, paying no heed to the Emperor's plea of sickness, proceeded to excommunicate, "with bell, book and candle," one whom he said had been nursed, tended, and aided by the Church, only to cheat her with false hopes and trickery.

A pretty quarrel now arose. Frederick appealed to the sovereigns of Europe, declaring that his illness had been real and that "the Christian charity which should hold all things together is dried at its very source."

Meantime he treated the ban of excommunication with contempt.

The Pope replied, in the ensuing Holy Week, by putting every place where Frederick happened to visit under an interdict, and threatening to absolve his subjects from their allegiance if this were disregarded. The Emperor took no notice, but, as though to emphasise the injustice with which he had been treated, pushed on his preparations for the Crusade. Setting out to Brindisi, he was met by papal envoys who forbade him to leave Italy until he had done penance for his offences against the Church. His only answer was to send his own messengers to Rome demanding that the interdict be removed, and meantime he set sail for Acre.

All other Crusaders had gone forth with the blessing of the Pope and the Church; this, the most recent of them all, came as an outcast, with the ban of the Church upon him; and his position was bound to be affected thereby. The greater part of his army feared to serve under him, and he landed with only six hundred knights, "more like a pirate than a great king."

The military orders, the Knights of the Hospital and the Temple also refused to acknowledge him, but the scattered pilgrims, eager for a leader at any price, looked upon him with favour and rallied to his standard.

But upon these broken reeds Frederick had little intention of leaning. From the bigoted narrowness of Templars and Hospitallers he gladly turned to the polished and cultivated Sultan, Malek-Camhel, who was quite prepared to renew friendly terms with one whom he held in much respect. For some time they dealt with trifles, comparing their respective skill in verse-making and in music. Then the Emperor sent Camhel his sword and cuirass, and the latter responded by a present of an elephant, some camels, and a quantity of the rich spices and stuffs of the East.

Becoming aware, at length, that these signs of friendship were the cause of mutterings of discontent in the camps both of Islam and of the Crusaders, they at length agreed upon a truce of ten years on the following conditions. The towns of Joppa, Bethlehem and Nazareth were to be given up to the Christians and the city of Jerusalem, with one important exception.