The complete investment of the city was impossible, and Frederic, in consequence, had established four distinct attacks, surrounded by strong palisades and deep ditches as a protection to the sorties of the besieged. Although, at intervals of distance, the camps commanded all the avenues of approach, and it was impossible for the garrison to receive any supplies or reinforcements, or hold any communication with the exterior. As it had been decided to reduce the place by famine, a rigid blockade was enforced, and the different leaders were relieved from the necessity of constructing any of those clumsy machines, under cover of which in those days the assaults upon the works were conducted. However, Henry the Lion had ordered the building of an immense tower whose proportions excited general astonishment. It was upon wheels, six stories in height, and could accommodate beneath it a thousand soldiers. The upper part was narrower and provided with doors, through which the garrison could pass, by means of temporary bridges, on to the walls of the city. Sorties from the town were of almost daily occurrence, and the personal hatred of the combatants gave to these engagements a most sanguinary character. Whilst the Italians were engaged in this work of mutual self-destruction, Frederic was preparing to submit them all to his Imperial sway. While the besieged were ready to suffer every extremity in defence of their sacred rights, the greatest agitation reigned in the camp of the Italian auxiliaries. Sworn enemies, for years detesting each other, they were now compelled to live in the forced proximity of a narrow camp. Leagued together by their common hatred for Milan, the old leaven still, at times, broke out into open violence, and it required the most stern and almost cruel severity of the Emperor to preserve anything like order among them. Frederic had learned, by experience, that fear was the only master whom they would obey. Rechberg perceived an immense crowd of strangers pressing towards the vast open space in the middle of the encampment. Jousts and military games were, in that age, so much the fashion, that, even under the walls of a beleaguered town, a place was set apart for the purpose. But on this occasion it seemed as though the crowd's attraction had another motive than mere amusement. Frederic's banner floated in the air, and the Imperial eagle fluttered bold and haughty above the multitude. On horseback, in the midst, stood a herald in a scarlet tabard and with a silver-mounted truncheon in his hand, and immediately behind him, a man, who, in a few weeks' time, had become the terror of the Italians. It was Hesso, the chief of the Imperial police, surrounded by his men fully armed. He glared fiercely upon the crowd. "What does that blood-thirsty dog want here?" was muttered on all sides. "See how he is looking for some new victims! the poor devils whom he hung this morning are hardly cold, before he wants to begin again!"