The militias of Bergamo, Brescia, Cremona, Mantua, Verona, and Treviso arrived the 27th of April, 1167, on the ground covered by the ruins of this great city. They apportioned among themselves the labour of restoring the enclosing walls; all the Milanese of the four villages, as well as those who had taken refuge in the more distant towns, came in crowds to take part in this pious work; and in a few weeks the new-grown city was in a state to repel the insults of its enemies. Lodi was soon afterwards compelled, by force of arms, to take the oath to the league; while the towns of Venice, Piacenza, Parma, Modena, and Bologna voluntarily and gladly joined the association. Frederick, meanwhile, arrived within sight of Rome. The Romans dared to await him in the open field; he defeated them with great slaughter, and made himself master of the Leonine city. The inhabitants still defending themselves in the Vatican, he dislodged them by setting fire to Santa Maria, the adjoining church; Alexander, in his fright, escaped by the Tiber. After his retreat the Romans took the oath of fidelity to the emperor, without, however, receiving his army within their walls; but fever, and the suffocating heat of the Campagna, soon began, by its ravages, to avenge the Italians; from the first days of August an alarming mortality broke out in the camp of the emperor. [Sidenote: [1167-1174 A.D.]] The princes to whom he was most attached, the captains in whom he had most confidence, two thousand knights, with a proportional number of common soldiers, were carried off in a few weeks. He endeavoured to flee from the destructive scourge; he traversed in his retreat Tuscany and the Lunigiana; but his route was marked with graves, in which every day, every hour, he deposited the bodies of his soldiers. He was no longer strong enough to vanquish even the opposition of the little town of Pontremoli, which refused him a passage; and it was by roads almost impracticable that he at length crossed the Apennines. He arrived at Pavia about the middle of September, and attempted to assemble a diet; but the deputies of Pavia, Novara, Vercelli, and Como alone obeyed his summons. He harangued the assembly with great vehemence; and, throwing down his glove, challenged the rebellious cities to a pitched battle. He passed the winter in combating, with his small remaining army, the league of Lombardy; but in the month of March, 1168, he escaped from the Italians, and repassed Mont Cenis, to return and arm the Germans anew against Italy.