Uguccione, finding himself growing worse, went to Montecarlo to be cured, and left the command of the army in the hands of Castruccio.  This change brought about the ruin of the Guelphs, who, thinking that the hostile army having lost its captain had lost its head, grew over-confident.  Castruccio observed this, and allowed some days to pass in order to encourage this belief; he also showed signs of fear, and did not allow any of the munitions of the camp to be used.  On the other side, the Guelphs grew more insolent the more they saw these evidences of fear, and every day they drew out in the order of battle in front of the army of Castruccio.  Presently, deeming that the enemy was sufficiently emboldened, and having mastered their tactics, he decided to join battle with them.  First he spoke a few words of encouragement to his soldiers, and pointed out to them the certainty of victory if they would but obey his commands.  Castruccio had noticed how the enemy had placed all his best troops in the centre of the line of battle, and his less reliable men on the wings of the army; whereupon he did exactly the opposite, putting his most valiant men on the flanks, while those on whom he could not so strongly rely he moved to the centre.  Observing this order of battle, he drew out of his lines and quickly came in sight of the hostile army, who, as usual, had come in their insolence to defy him.  He then commanded his centre squadrons to march slowly, whilst he moved rapidly forward those on the wings.  Thus, when they came into contact with the enemy, only the wings of the two armies became engaged, whilst the center battalions remained out of action, for these two portions of the line of battle were separated from each other by a long interval and thus unable to reach each other.  By this expedient the more valiant part of Castruccio’s men were opposed to the weaker part of the enemy’s troops, and the most efficient men of the enemy were disengaged; and thus the Florentines were unable to fight with those who were arrayed opposite to them, or to give any assistance to their own flanks.  So, without much difficulty, Castruccio put the enemy to flight on both flanks, and the centre battalions took to flight when they found themselves exposed to attack, without having a chance of displaying their valour.  The defeat was complete, and the loss in men very heavy, there being more than ten thousand men killed with many officers and knights of the Guelph party in Tuscany, and also many princes who had come to help them, among whom were Piero, the brother of King Ruberto, and Carlo, his nephew, and Filippo, the lord of Taranto.  On the part of Castruccio the loss did not amount to more than three hundred men, among whom was Francesco, the son of Uguccione, who, being young and rash, was killed in the first onset.