what diplomacy could effect in favour of Lorenzo de’ Medici. In 1478 Florence made a creditable resistance against superior forces. The fortification of Poggio Imperiale blocked the Val d’Elsa, the most vulnerable approach to [Sidenote: Campaigns of 1478 and 1479.] the city; and when the disappointed invaders turned eastwards to the valley of the Chiana, they had only completed the preliminary operation of taking Monte San Savino when winter put an end to operations. But in the campaign of 1479 fortune turned decisively against the Florentines. A revolution in Milan, which was dexterously organised by Ferrante, not only compelled the withdrawal of the Milanese troops; but by substituting the rule of Ludovico Sforza for that of Bona of Savoy, detached Milan for a time from the Florentine alliance. The Turkish attack on Scutari, which reduced Venice to such straits that it was necessary to make the peace of Constantinople, and to refrain from any vigorous action in Italy, was also attributed by contemporary suspicion to the wily suggestions of the Neapolitan king. Worst of all, France would not take action. A few hundred French lances would have been worth far more than the threat of a general council which the Pope knew would not be carried out. Florence found herself isolated and exposed to a crushing attack. The plague broke out within the walls, Poggio Imperiale was stormed, and nothing but the ponderous tactics of a mercenary army saved the city from the necessity of an ignominious surrender. Lorenzo de’ Medici was in a very difficult position. In a sense the city was enduring these sufferings and risks on his behalf, and the loyalty of the citizens might give way under an intolerable strain. He sought and found a way out of the dilemma by an enterprise which his adherents and apologists have agreed to consider [Sidenote: Lorenzo goes to Naples.] heroic. In December 1479 he set out on an embassy to Naples. The fate of Jacopo Piccinino was sufficiently recent to convince people that it was dangerous to trust to the good faith of Ferrante, yet it is difficult to believe that Lorenzo undertook the journey without some fairly substantial assurance that there was less risk in it than appeared on the surface. After all, Ferrante had originally been the cordial friend of Lorenzo; and although he had since then taken offence, he might be appeased by a renewal of the old understanding. Events had proved that it was not worth while to alienate Naples in order to establish better relations with Venice, and Lorenzo was quite willing to do penance for his blunder. And the alliance between Naples and the Pope did not rest upon very substantial foundations. Lorenzo could point out that Sixtus only cared for the aggrandisement of his nephew, that he was already preparing to expel the Ordelaffii from Forli in order to give a duchy to Girolamo, and that a strong secular power in the papal states was by no means likely to benefit Naples.