Another prolonged and sanguinary conflict with Sienna was undertaken and resumed almost yearly from 1227 to 1235. The Siennese suffered severe losses, but were able to seize Montepulciano, demolish its towers and ramparts, and do some damage to Montalcino, which had joined alliance with the Florentines. The latter, however, not only devastated the Siennese _contado_ time after time, and captured a large number of prisoners, but also besieged the hostile capital, and although failing to win it, pressed close enough to the walls to hurl donkeys over them with catapults, to prove their contempt for the town. Finally, through the mediation of the Pope, peace was concluded very advantageously for Florence. The Siennese had to forfeit a large sum of money for the rebuilding of the walls and towers of Montepulciano, were sworn to leave that territory for ever unmolested, and likewise compelled to repair the castle of Montalcino, at the pleasure of the Florentines, who still retained their hold on Poggibonsi. II. Thus, throughout all these wars, in which the influence of Pope and emperor was felt on this or the other side, we are enabled to trace the gradual formation of parties in Tuscany, and to witness the process by which the political and commercial supremacy of Florence was built up. Her present rivals, Sienna and Pisa, both adhere to the Empire; whereas Florence clings more and more closely to the Church. Pisa shuts her out from the sea: hence the origin of their mutual rivalry and continual strife. How, indeed, could war be avoided, when the commercial power of Florence felt the increasingly imperative need of free access to the coast? Sienna, on the other hand, competed with Florence by trying to get all the affairs of the Roman _curia_ into the hands of its own bankers, those affairs being so numerous and lucrative as to enrich all concerned with them. These continual jealousies invariably urged Pisa and Sienna to favour the Empire. Lucca, as the rival of Pisa, inclined towards Florence, and became Guelph. Pistoia, planted between two Guelph cities, and continually menaced by them, naturally adopted the Ghibelline cause. Thus, the division of parties in Tuscany afterwards reacted on the formation of Florentine sects, and as the latter began to assume a more general character, through the growing influence of Frederic II. in Italy, they adopted the German names of Guelphs and Ghibellines. The Florentine Republic, having triumphed over Pisa, Sienna, and Pistoia, was virtually the chief power in Tuscany; but had one danger to face, in the possible augmentation of Frederic's power. Frederic II. was the enemy of the Pope, who had excommunicated him, and of all Guelphs! He had gone away for a time to lead the Crusade in the East; was now in Germany engaged in a struggle with his rebellious son, and all this had greatly advanced the fortunes of Florence. But he was about to return to Italy, and his presence