But the Germans who accompanied the emperor, notwithstanding the ardour with which they had undertaken this distant expedition, began to grow tired of so long an absence from their home. The license extended to their pillage and debauchery no longer appeared to them a sufficient compensation for tedious marches and the dangers of war. They pressed the emperor to advance towards Rome, and to avoid all quarrel with the great towns by which they passed, although almost all refused to admit them within their walls--providing subsistence and lodging for them in the suburbs only. The impossibility of maintaining discipline in a rapacious army, which beheld for the first time the unknown riches of commerce and the arts; the difficulty of avoiding quarrels between two nations, neither of which understood the language of the other, perhaps justified this precaution. Frederick thus passed by Piacenza, Parma, Bologna, and Florence. He was not received even into Rome; his troops occupied what was styled the Leonine city, or the suburb built round the Vatican; he was there crowned by the pope, Adrian IV, while his army was obliged to repel the Romans, who advanced by the bridge of St. Angelo and the Borgo[6] of Trastevere to disturb the ceremony. Frederick withdrew from Rome the following day; conducting his army into the mountains to avoid the great heat of summer. The citizens of Spoleto, not having supplied with sufficient haste the provisions he demanded, he attacked, took, and burned their city; sickness, however, began to thin the ranks of his soldiers; many also deserted, to embark at Ancona. Frederick, with a weakened army, directed his march on Germany by the valleys of the Tyrol. The citizens of Verona, who would not admit the Germans within their walls, constructed for him a bridge of boats on the Adige, which he hastily passed over, but had hardly gained the opposite bank, when enormous pieces of wood, carried down by the impetuosity of the current, struck and destroyed the bridge. Frederick had no doubt that the Lombards had laid this snare for him, and flattered themselves with the breaking of the bridge whilst he should be in the act of passing over; but he was no longer sufficiently strong to avenge himself. [Sidenote: [1155-1158 A.D.]]