The year was 897, and the pope was Stephen VI. During this less-than-stellar period of papal history, Stephen undertook one of the strangest actions in the history of the papacy. Formosus, Stephen’s predecessor as pope, chose to back the faction of Arnulf, king of the East Franks, and named him Holy Roman Emperor after having already crowned Lambert of Spoleto.
Stephen was an opponent of Arnulf, and chose to put Formosus on trial. The major problem with this plan was the fact that Formosus was already dead. However, this inconvenience did not dissuade Stephen from exhuming the body of Formosus, who was promptly put on trial for transferring the bishopric of Porto to Rome. While the official charge dealt with canon law, the real reason for the trial was a desire for the destruction of the Catholic faction that followed Formosus.
The court dressed Formosus, who had already been dead for nine months, in the normal papal finery and conducted a show trial while the corpse sat on the papal throne. Unsurprisingly, Formosus had nothing to say in his defense. Because of this inability to defend himself, the court declared the former pope guilty and effectively annulled his papacy. As punishment for his crimes, the exhumed body of Pope Formosus was dragged through the streets of Rome and disposed of unceremoniously in the Tiber River.