Villani's Chronicle (v. 39) now gives a list of the principal Guelph and Ghibelline families, showing that the majority of the older houses was almost invariably Ghibellines, whereas the Guelph party included many "of no great antiquity," but "already beginning to be powerful." Later on, when the Ghibellines are destroyed, we shall find the Guelph nobles merged in the party of the well-to-do burghers (_popolo grasso_). At present these patricians, being hostile to the Uberti, begin to make advances to newly enriched families, and even to the people, by siding with the Church. Fortunately Pope Innocent III. started a Crusade at this time, and thus many powerful Florentines went to the East and employed their fighting powers in a better cause. At the siege of Damietta, in fact, they distinguished themselves greatly: Bonaguisa dei Bonaguisi the first to scale the walls, planted the banner of the Republic beside the Christian flag. In Giovanni Villani's time this banner was still preserved and held in the greatest honour. In 1218 Florence resumed hostilities in the _contado_, and by 1220 had subdued various castles and domains, and exacted oaths of fealty from all defeated foes. But immediately afterwards a far graver war broke out with Pisa. The jealousy of the two rival republics was always on the increase, and for some time past each had struggled against the other for absolute commercial supremacy in Tuscany. Pisa commanded the sea, Florence the mainland, therefore each city required the other's help. Hence, in spite of repeated agreements and treaties, their mutual jealousy remained undiminished. The Florentines adhered steadfastly to the Church; the Pisans to the Empire. Things had gradually become inflamed to so high a pitch that the smallest trifle was enough to excite war, or rather to provoke the endless series of wars destined to change the character of the Tuscan factions.