In 1173 (as the most recent historian of Florence has shown, and not in the eleventh century as formerly supposed), the second circle of walls was built, and included a much larger tract of city, though many of the churches which we have been wont to consider the most essential things in Florence stand outside them. A new Porta San Piero, just beyond the present façade of the ruined church of San Piero Maggiore, enclosed the Borgo di San Piero; thence the walls passed round to the Porta di Borgo San Lorenzo, just to the north of the present Piazza, and swept round, with two gates of minor importance, past the chief western Porta San Pancrazio or Porta San Paolo, beyond which the present Piazza di Santa Maria Novella stands, down to the Arno where there was a Porta alla Carraia, at the point where the bridge was built later. Hence a lower wall ran along the Arno, taking in the parts excluded from the older circuit down to the Ponte Vecchio. About half-way between this and the Ponte Rubaconte, the walls turned up from the Arno, with several small gates, until they reached the place where the present Piazza di Santa Croce lies–which was outside. Here, just beyond the old site of the Amphitheatre, there was a gate, after which they ran straight without gate or postern to San Piero, where they had commenced.
Instead of the old Quarters, named from the gates, the city was now divided into six corresponding Sesti or sextaries; the Sesto di Porta San Piero, the Sesto still called from the old Porta del Duomo, the Sesto di Porta Pancrazio, the Sesto di San Piero Scheraggio (a church near the Palazzo Vecchio, but now totally destroyed), and the Sesto di Borgo Santissimi Apostoli–these two replacing the old Quarter of Porta Santa Maria. Across the river lay the Sesto d'Oltrarno–then for the most part unfortified. At that time the inhabitants of Oltrarno were mostly the poor and the lower classes, but not a few noble families settled there later on. The Consuls, the supreme officers of the state, were elected annually, two for each sesto, usually nobles of popular tendencies; there was a council of a hundred, elected every year, its members being mainly chosen from the Guilds as the Consuls from the Towers; and a Parliament of the people could be summoned in the Piazza. Thus the popular government was constituted.
Hardly had the new walls risen when the Uberti in 1177 attempted to overthrow the Consuls and seize the government of the city; they were partially successful, in that they managed to make the administration more aristocratic, after a prolonged civil struggle of two years' duration. In 1185 Frederick Barbarossa took away the privileges of the Republic and deprived it of its contrada; but his son, Henry VI., apparently gave it back. With the beginning of the thirteenth century we find the Consuls replaced by a Podestà, a foreign noble elected by the citizens themselves; and the Florentines, not content with having back their contrada, beginning to make wars of conquest upon their neighbours, especially the Sienese, from whom they exacted a cession of territory in 1208.
In 1215 there was enacted a deed in which poets and chroniclers have seen a turning point in the history of Florence. Buondelmonte dei Buondelmonti, "a right winsome and comely knight," as Villani calls him, had pledged himself for political reasons to marry a maiden of the Amidei family–the kinsmen of the proud Uberti and Fifanti. But, at the instigation of Gualdrada Donati, he deserted his betrothed and married Gualdrada's own daughter, a girl of great beauty. Upon this the nobles of the kindred of the deserted girl held a council together to decide what vengeance to take, in which "Mosca dei Lamberti spoke the evil word: Cosa fatta, capo ha; to wit, that he should be slain; and so it was done." On Easter Sunday the Amidei and their associates assembled, after hearing mass in San Stefano, in a palace of the Amidei, which was on the Lungarno at the opening of the present Via Por Santa Maria; and they watched young Buondelmonte coming from Oltrarno, riding over the Ponte Vecchio "dressed nobly in a new robe all white and on a white palfrey," crowned with a garland, making his way towards the palaces of his kindred in Borgo Santissimi Apostoli. As soon as he had reached this side, at the foot of the pillar on which stood the statue of Mars, they rushed out upon him. Schiatta degli Uberti struck him from his horse with a mace, and Mosca dei Lamberti, Lambertuccio degli Amidei, Oderigo Fifanti, and one of the Gangalandi, stabbed him to death with their daggers at the foot of the statue. "Verily is it shown," writes Villani, "that the enemy of human nature by reason of the sins of the Florentines had power in this idol of Mars, which the pagan Florentines adored of old; for at the foot of his figure was this murder committed, whence such great evil followed to the city of Florence." The body was placed upon a bier, and, with the young bride supporting the dead head of her bridegroom, carried through the streets to urge the people to vengeance. Headed by the Uberti, the older and more aristocratic families took up the cause of the Amidei; the burghers and the democratically inclined nobles supported the Buondelmonti, and from this the chronicler dates the beginning of the Guelfs and Ghibellines in Florence.
But it was only the names that were then introduced, to intensify a struggle which had in reality commenced a century before this, in 1115, on the death of Matilda. As far as Guelf and Ghibelline meant a struggle of the commune of burghers and traders with a military aristocracy of Teutonic descent and feudal imperial tendencies, the thing is already clearly defined in the old contest between the Uberti and the Consuls. This, however, precipitated matters, and initiated fifty years of perpetual conflict. Dante, through Cacciaguida, touches upon the tragedy in his great way in Paradiso XVI., where he calls it the ruin of old Florence.
"La casa di che nacque il vostro fleto,
per lo giusto disdegno che v'ha morti
e posto fine al vostro viver lieto,
era onorata ed essa e suoi consorti.
O Buondelmonte, quanto mal fuggisti
le nozze sue per gli altrui conforti!
Molti sarebbon lieti, che son tristi,
se Dio t'avesse conceduto ad Ema
la prima volta che a città venisti.
Ma conveniasi a quella pietra scema
che guarda il ponte, che Fiorenza fesse
vittima nella sua pace postrema."5
And again, in the Hell of the sowers of discord, where they are horribly mutilated by the devil's sword, he meets the miserable Mosca.
"Ed un, ch'avea l'una e l'altra man mozza,
levando i moncherin per l'aura fosca,
sì