Induced to summon at his capital in June 415 a synod at which Orosius communicated the decisions of Carthage and read such of Augustine's writings against Pelagius as had at that time appeared.
If Frederick had only come in person, a single month of his presence might have meant everything: if Pelagius had only listened to King John, the sultan was ready to concede practically everything which was at issue.
Damietta was taken without a blow, and the march for Cairo was begun, as it had been begun by the legate Pelagius in 1221.
In one source the great heresiarch Pelagius is stated to have been a Scot.
His principal works are Historia Pelagiana sive Historiae de controversies quas Pelagius ejusque reliquiae moverunt (1618); Aristarchus, sive de arte grammatica (1635 and 1695; new ed.
The letter of the pope informing Pelagius of this delay is dated the 10th of June: it would probably reach his hands after his departure from Damietta; and thus the Cardinal gave the signal for the march, when, as he thought, the emperor's coming was imminent.
The crusaders were driven back towards Damietta; and at the end of August 1221 Pelagius had to make a treaty with Malik-al-Kamil, by which he gained a free retreat and the surrender of the Holy Cross at the price of the restoration of Damietta.