The first assault on the wall was repulsed, but the defenders, hugely outnumbered and lacking ammunition, were soon reduced to throwing rocks at those they called “half-castes” and “Lutherans.” Up went the scaling ladders, and soon Germans and Spaniards were swarming over the wall. Some of the defenders fought bravely, including the pope’s Swiss Guards, but they were quickly overwhelmed.

By the time Clement had crossed the wall the fighting was all but done. It was still dawn; still mist from the Tiber choked the city streets. Afterward, Rome was at the mercy of the Emperor’s troops. Later, Clement would remember little of the days that followed, little save bloodstained glimpses of unbelievable savagery.

The Romans were cut to pieces, even if unarmed, even if unable to defend themselves. Even invalids in hospitals were slaughtered.

The doors of churches, convents, palaces, and monasteries were broken down and their contents hurled into the streets. When people tried to shelter in the churches they were massacred; five hundred died even in Saint Peter’s. Priests were forced to take part in obscene travesties of the Mass, and if they did not they were eviscerated, or crucified, or dragged through the streets, naked and in chains. Nuns were violated, and used as tokens in games of chance, and convents were turned into brothels where the women of the upper classes were forced into prostitution. Holy relics were abused; the skull of the Apostle Andrew was kicked around the streets, the handkerchief of Saint Veronica was sold in an inn, the spear said to have pierced Christ’s side was displayed like a battle trophy by a German.

Clement took part in the torment of one wealthy man who was made to rape his own daughter, and another, a very fat man, who was forced to eat his own roasted testicles. Afterward he would not be able to credit what he had done.

The Sack of Rome was the end product of decades of suspicion, jealousy, and hostility. The Renaissance popes had been great patrons of the arts, but they had acted like ambitious princelings and made many enemies. Meanwhile the great wealth of Rome had made the city a prize that the European powers, especially France and Spain, had eyed with jealousy. French, Spaniards, and landless German Lutherans had at last made common cause under Charles’s imperial banner. But none of this could have justified the Sack.

It went on for months. It was said that twelve thousand were killed. Two-thirds of the housing stock was burned to the ground. On the resulting wasteland lay putrefying corpses, gnawed by dogs. Even on Sundays not a church bell sounded, across the whole of Rome.