Meanwhile, in 1250, the year now claiming our attention, Frederic II. passed away, his son Enzo lay captive in Bölogna, Innocent IV. was stirring the Guelphs to action, and Pietro of Verona had become the scourge of all heretics and foes of the Papacy in Tuscany and Lombardy. Accordingly the Ghibelline domination in Florence was approaching its end. In fact, from the moment that the emperor withdrew into Apulia, already stricken with mortal disease, the Guelphs showed so much boldness that the Ghibellines decided on a fresh expedition to oust them from the Castle of Ostina, in the Valdarno, where they had assembled in great force. But while laying siege to the stronghold the Ghibellines were compelled to keep a strong reserve at Figline to protect their rear from the many Guelph partisans lurking at Montevarchi. The latter, however, made a night attack on the force encamped at Figline, and routed it so thoroughly that when the news reached Ostina the Ghibellines raised the siege and marched back to the capital. Thereupon both the people and burghers of Florence, tired of the unbearable load of taxation imposed on them by the continual wars undertaken by the Ghibellines, and worn out by the "grave extortions and acts of violence of these tyrannical masters," felt that the moment for vengeance had come, and rose in open revolt. The rebels were led by the more influential citizens of the so-called middle class, then acting as heads of the people. These men first held their sittings in the Church of San Firenze, then in Santa Croce, and finally, still dreading attack from the Uberti, assembled in smaller numbers and with greater safety in the houses of the Anchioni family. Here, in October, 1250, they proclaimed the nomination of thirty-six "Corporals of the people," six to each _sestiere_, forming the basis of the third Florentine Constitution, known as the First Popular Government (_Primo Popolo_), because its main purpose was to organise and strengthen the people in opposition to the nobles, and by this time the latter being much disheartened, unresistingly submitted to the new government. The first measure adopted was the dismissal of all the magistrates in office, and reforms were then undertaken. The post of Podestà was retained, and henceforth this official became still more exclusively the head of the patricians, being now counterbalanced by the newly instituted Captain of the people, as chief of the _popolani_. But, as in this way the Republic was divided in two parts, a central, presiding body was established consisting of twelve elders (_anziani_) of the people, two for each _sestiere_. These _anziani_ had some of the attributes of the Consuls of former days, with this difference, however, that not only were they men of the people, but that the chief government of the city was now entrusted to the Podestà and the Captain. In fact, the new and most important part of the reform