sagacity and diplomatic skill were required in order to multiply the resources of the Republic, and the Florentines proved equal to the occasion. VII. Although the city of Pisa derived all its strength and influence from its maritime trade, nevertheless--either from being always on the Imperial side, or because such was the predestined fate of all Italian sea-board republics--it was dominated by a powerful aristocracy to the same extent as were Genoa and Venice. With their usual astuteness, the Florentines had long sought to bring their influence to bear on the Pisan nobles, in order to create discord among them. Giovanni Visconti, entitled Judge of Gallura, from the high and remunerative post once held by him in Sardinia, as governor of several provinces, for the Pisan Republic, had been subsequently (1274) exiled on account of his Guelph proclivities, and had then joined the vicar of King Charles and the Guelph League against his native state. He died in 1275; and just at that time Count Ugolino della Gherardesca, one of the most powerful and ambitious nobles of Pisa, who aspired to establish a despotism there, was driven into banishment with other formidable Guelphs (1275). These exiles not only made alliance with the Florentines, but, in conjunction with the League, or _Taglia_, made war on Pisa and captured several castles, Vico Pisano included. In the September of the same year they returned to the attack in co-operation with the Angevin vicar-royal, Florentines, and Lucchese, and, defeating their fellow-citizens at three miles' distance from Pisa, seized the Castle of Asciano, which was handed over to the Lucchese. In 1276 the war was resumed by Florence and Lucca, and again at the instigation of Count Ugolino and his friends. This was the occasion alluded to at an earlier page, when both sides brought powerful armies into the field and came to a pitched battle between Pisa and Pontedera, on the banks of the so-called Fosso Arnonico, a canal into which the Pisans had formerly diverted the waters of the Arno for the better defence of their territory. Again the Pisans were worsted, and the bitterness of defeat enhanced by having to accept peace on the terms proposed by Florence, of which the first and hardest condition was the readmittance in their city of all the banished Guelphs, and particularly of the ambitious Count Ugolino, whom they hated so deeply.