The next morning being come, at nine o’clock, according to agreement, they took arms, and at the call of liberty assembled, each party in its own district, under the ensigns and with the arms of the people, which had been secretly provided by the conspirators.  All the heads of families, as well of the nobility as of the people, met together, and swore to stand in each other’s defense, and effect the death of the duke; except some of the Buondelmonti and of the Cavalcanti, with those four families of the people which had taken so conspicuous a part in making him sovereign, and the butchers, with others, the lowest of the plebeians, who met armed in the piazza in his favor.

The duke immediately fortified the place, and ordered those of his people who were lodged in different parts of the city to mount upon horseback and join those in the court; but, on their way thither, many were attacked and slain.  However, about three hundred horse assembled, and the duke was in doubt whether he should come forth and meet the enemy, or defend himself within.  On the other hand, the Medici, Cavicciulli, Rucellai, and other families who had been most injured by him, fearful that if he came forth, many of those who had taken arms against him would discover themselves his partisans, in order to deprive him of the occasion of attacking them and increasing the number of his friends, took the lead and assailed the palace.  Upon this, those families of the people who had declared for the duke, seeing themselves boldly attacked, changed their minds, and all took part with the citizens, except Uguccione Buondelmonti, who retired into the palace, and Giannozzo Cavalcanti, who having withdrawn with some of his followers to the new market, mounted upon a bench, and begged that those who were going in arms to the piazza, would take the part of the duke.  In order to terrify them, he exaggerated the number of his people and threatened all with death who should obstinately persevere in their undertaking against their sovereign.  But not finding any one either to follow him, or to chastise his insolence, and seeing his labor fruitless, he withdrew to his own house.

In the meantime, the contest in the piazza between the people and the forces of the duke was very great; but although the place served them for defense, they were overcome, some yielding to the enemy, and others, quitting their horses, fled within the walls.  While this was going on, Corso and Amerigo Donati, with a part of the people, broke open the stinche, or prisons; burnt the papers of the provost and of the public chamber; pillaged the houses of the rectors, and slew all who had held offices under the duke whom they could find.  The duke, finding the piazza in possession of his enemies, the city opposed to him, and without any hope of assistance, endeavored by an act of clemency to recover the favor of the people.  Having caused those whom he had made prisoners to be brought before him, with amiable and kindly expressions