The king being at Tivoli, and designing to pursue his enterprise against Tuscany, as had been arranged between himself and Filippo, judging that the war now commenced in Lombardy would give him both time and opportunity, and wishing to have a footing in the Florentine state before he openly commenced hostilities, opened a secret understanding with the fortress of Cennina, in the Val d'Arno Superiore, and took possession of it. The Florentines, surprised with this unexpected event, perceiving the king already in action, and resolved to do them all the injury in his power, hired forces, created a council of ten for management of the war, and prepared for the conflict in their usual manner. The king was already in the Siennese, and used his utmost endeavors to reduce the city, but the inhabitants of Sienna were firm in their attachment to the Florentines, and refused to receive him within their walls or into any of their territories. They furnished him with provisions, alleging in excuse, the enemy's power and their inability to resist. The king, finding he could not enter by the Val d'Arno, as he had first intended, both because Cennina had been already retaken, and because the Florentines were now in some measure prepared for their defense, turned toward Volterra, and occupied many fortresses in that territory. Thence he proceeded toward Pisa, and with the assistance of Fazio and Arrigo de' Conti, of the Gherardesca, took some castles, and issuing from them, assailed Campiglia, but could not take it, the place being defended by the Florentines, and it being now in the depth of winter. Upon this the king, leaving garrisons in the places he had taken to harass the surrounding country, withdrew with the remainder of his army to quarters in the Siennese. The Florentines, aided by the season, used the most active exertions to provide themselves troops, whose captains were Federigo, lord of Urbino, and Gismondo Malatesti da Rimino, who, though mutual foes, were kept so united by the prudence of the commissaries, Neri di Gino and Bernardetto de' Medici, that they broke up their quarters while the weather was still very severe and recovered not only the places that had been taken in the territory of Pisa, but also the Pomerancie in the neighborhood of Volterra, and so checked the king's troops, which at first had overrun the Maremma, that they could scarcely retain the places they had been left to garrison.