At Florence the course of affairs was not much affected by the reverses which befell Charles. At the same time, these, and a success gained by Guy of Montefeltro over John of Appia, a French officer whom Martin had appointed Count of Romagna, made the Guelf majority uneasy. Cardinal Latino’s Constitution was abandoned, and a new form of government adopted. The trading-class resolved to get rid altogether of the representatives of feudal authority, weak as they had become,[26] and to this end the Fourteen were abolished, and the chief power placed in the hands of the Priors of the Arts, or, as we should say, the Masters of the great trading guilds. The number of those guilds which contributed members to the governing body seems to have been gradually increased. At first only three--the Clothmakers, the Money-changers, and the Wool-dealers--were thus honoured; but by the end of the century, at least twelve, seven greater and five lesser arts, were included. The Priors, as the Fourteen had done, held office for two months only, and various devices were employed to prevent any house or any person from becoming dangerously powerful. Nobles, in order to qualify for office, had to join a guild; and as the nobles, or _grandi_, were more frequently on the Ghibeline side, this would yet further weaken that party. Florence had now fairly entered upon a period of great prosperity. Her bankers lent money to kings; her trade extended all over Europe. Pisa, her most dangerous rival, had been utterly crushed by the Genoese in the great sea-fight off Meloria, with a slaughter which seems to have struck awe into the hearts even of the victors; and though she expelled her Guelfs four years later, in 1288, and, in 1291, under the brilliant leader Guy of Montefeltro, won some successes in the field, she was never again a power to be feared. Arezzo gave some trouble as a rendezvous for the banished Ghibelines; but the battle of Campaldino, in 1289, already referred to, broke her strength for a long time. Florence was thus free to attend to the arts of peace. The city walls were extended and new gates built; and several of the buildings, which to this day are among the glories of Florence, date from that period. Still, however, much of the old class-jealousy smouldered; and, as Machiavelli points out, all fear of the Ghibelines being removed, the powerful houses began to oppress the people. Giano della Bella, himself of noble family, casting in his lot with the commons, succeeded in carrying what were called the Ordinances of Justice, whereby, among other things, nobles were absolutely disqualified from taking any part in the government. A measure so oppressive as this was bound to bring about its own appeal, and, as a matter of fact, within two years from its promulgation, Giano was driven into exile, and the nobles were more turbulent than ever. It is at this time that the name of Corso Donati first comes into prominence.