The Florentines, having occupied San Miniato, held a council of war to decide whether they should attack Pisa or the army of Castruccio, and, having weighed the difficulties of both courses, they decided upon the latter.  The river Arno was at that time low enough to be fordable, yet the water reached to the shoulders of the infantrymen and to the saddles of the horsemen.  On the morning of 10 June 1328, the Florentines commenced the battle by ordering forward a number of cavalry and ten thousand infantry.  Castruccio, whose plan of action was fixed, and who well knew what to do, at once attacked the Florentines with five thousand infantry and three thousand horsemen, not allowing them to issue from the river before he charged them; he also sent one thousand light infantry up the river bank, and the same number down the Arno.  The infantry of the Florentines were so much impeded by their arms and the water that they were not able to mount the banks of the river, whilst the cavalry had made the passage of the river more difficult for the others, by reason of the few who had crossed having broken up the bed of the river, and this being deep with mud, many of the horses rolled over with their riders and many of them had stuck so fast that they could not move.  When the Florentine captains saw the difficulties their men were meeting, they withdrew them and moved higher up the river, hoping to find the river bed less treacherous and the banks more adapted for landing.  These men were met at the bank by the forces which Castruccio had already sent forward, who, being light armed with bucklers and javelins in their hands, let fly with tremendous shouts into the faces and bodies of the cavalry.  The horses, alarmed by the noise and the wounds, would not move forward, and trampled each other in great confusion.  The fight between the men of Castruccio and those of the enemy who succeeded in crossing was sharp and terrible; both sides fought with the utmost desperation and neither would yield.  The soldiers of Castruccio fought to drive the others back into the river, whilst the Florentines strove to get a footing on land in order to make room for the others pressing forward, who if they could but get out of the water would be able to fight, and in this obstinate conflict they were urged on by their captains.  Castruccio shouted to his men that these were the same enemies whom they had before conquered at Serravalle, whilst the Florentines reproached each other that the many should be overcome by the few.  At length Castruccio, seeing how long the battle had lasted, and that both his men and the enemy were utterly exhausted, and that both sides had many killed and wounded, pushed forward another body of infantry to take up a position at the rear of those who were fighting; he then commanded these latter to open their ranks as if they intended to retreat, and one part of them to turn to the right and another to the left.  This cleared a space of which the Florentines at once took advantage, and