Pope Formosus’ Trial in the Cadaver Synod

A Dark History: the Popes: Vice, Murder, and Corruption in the Vatican by Brenda Ralph Lewis
A Dark History: the Popes: Vice, Murder, and Corruption in the Vatican by Brenda Ralph Lewis


Introduction to the Cadaver Synod

The Cadaver Synod, also known as the Cadaver Trial (Latin: Synodus Horrenda), refers to the posthumous ecclesiastical trial of Pope Formosus. Conducted in January 897 in Rome’s Basilica of St. John Lateran, the trial occurred seven months after Formosus’ death. His successor’s successor, Pope Stephen VI, orchestrated the trial, exhuming Formosus’ corpse for a papal court judgment. Formosus faced charges of perjury, illegal ascension to the papacy, and holding multiple bishoprics simultaneously. He was ultimately found guilty, and his papacy was invalidated.

Historical Context

This event unfolded during Italy’s politically turbulent period from the mid-9th to mid-10th centuries, characterized by frequent changes in the papacy. From 872 to 965, about two dozen popes were appointed, with nearly annual changes between 896 and 904. This instability reflected the influence of Roman political factions, although details are scant due to limited sources.

Formosus’ Early Career

Formosus’ rise in the ecclesiastical hierarchy began in 864 when he was appointed Bishop of Porto-Santa Rufina. This appointment occurred during the pontificate of Pope Nicholas I, a period marked by significant church reform and the consolidation of papal authority. Formosus, recognized for his abilities and piety, was entrusted with this important diocese, which played a vital role in the administration of the church.

Two years later, in 866, Formosus’ reputation as a capable church leader led to his appointment as a papal legate to Bulgaria. During this mission, he demonstrated exceptional diplomatic and religious acumen, effectively representing the interests of the papacy and spreading Christian teachings. His success in Bulgaria was so pronounced that Boris I, the ruler of Bulgaria, was deeply impressed. Acknowledging Formosus’ influence and leadership, Boris I requested that Pope Nicholas I appoint Formosus as the Archbishop of Bulgaria. This was a significant request, indicating the high regard in which Formosus was held by the Bulgarian court.

However, Pope Nicholas I denied this request, adhering to the ecclesiastical laws established by the Second Council of Nicaea. According to the fifteenth canon of this council, a bishop was forbidden to oversee more than one diocese. This rule was intended to prevent the accumulation of power and resources by individual bishops, ensuring a more equitable and decentralized church structure. Nicholas I’s refusal to appoint Formosus as Archbishop of Bulgaria was in line with maintaining this church law and avoiding the creation of ecclesiastical ‘fiefdoms.’

Beyond his work in Bulgaria, Formosus was also known for his travels to other significant centers of power. He visited Constantinople, the capital of the Byzantine Empire, which was a major religious and political hub during this period. Additionally, Formosus made his way to the Carolingian court, where he encountered Arnulf of Carinthia. Arnulf, a member of the Carolingian dynasty, was a Frankish king with aspirations to the Italian throne. Formosus’ interactions with such influential figures underscore his important role in the political and religious affairs of the time, further highlighting his stature as a significant ecclesiastical figure in medieval Europe.

Conflict and Excommunication

Pope John VIII’s reign witnessed Formosus fleeing Rome in 875 due to fear, followed by his excommunication in 876 for allegedly conspiring to usurp the papacy and influencing the Bulgarians against other bishops. In 879, Pope John VIII possibly reaffirmed this excommunication and legislated against ecclesiastical plunder. The accounts of Formosus’ presence at a council in Troyes and his subsequent oath to remain a layman are debated.

Resumption and Papacy

Following the death of Pope John VIII in 882, a significant shift occurred in the ecclesiastical landscape of Rome. Formosus, who had previously faced tension and conflict under John VIII’s papacy, found an opportunity to return to his ecclesiastical duties. He resumed his role as Bishop of Porto-Santa Rufina, a position he had held before the tumultuous events that led to his excommunication and subsequent controversies.

In 891, after several years of serving diligently in his reinstated role, Formosus was elected to the papacy. This elevation to the highest position within the Catholic Church was a remarkable turnaround, considering his earlier exile and condemnation. His election as Pope was indicative of his respected status within the church hierarchy and possibly a reflection of the changing political and religious dynamics in Rome and the broader Christian world.

Political Underpinnings of the Cadaver Synod

However, the conflicts and accusations from his past did not fade away with his ascension to the papacy. The earlier disputes with Pope John VIII, particularly the accusations and excommunication, lingered and formed the foundation for the charges brought against him posthumously at the Cadaver Synod. The Synod, convened by Pope Stephen VI in 897, seven months after Formosus’ death, revisited these past conflicts in a bizarre and unprecedented manner.

At the Cadaver Synod, Formosus was accused of perjury and illegally holding the office of bishop as a layman. These charges were likely linked to his actions and statements made during the Council of Troyes. According to some historical accounts, at the Council of Troyes, Formosus had been compelled to take an oath, possibly under duress or as part of his reconciliation with the church, to remain a layman for the rest of his life and to refrain from entering Rome or resuming his former see at Porto. This oath, if it indeed occurred as described by some sources, would have conflicted with his later role as a bishop and eventually as Pope, thus providing grounds for the posthumous charges of perjury and illegal bishopric.

The Cadaver Synod likely had other political motivations. Pope Formosus, during his papacy, engaged in several key political maneuvers that had significant implications for the power dynamics within the Holy Roman Empire. Notably, his actions regarding Lambert of Spoleto and Arnulf of Carinthia were pivotal.

Formosus crowned Lambert of Spoleto, a significant political figure, indicating an alliance or at least a strategic partnership. This crowning was a substantial political act, as the Pope’s endorsement greatly influenced the legitimacy and power of rulers during this era. However, the political climate was volatile, and alliances were often fluid. Recognizing the emerging threat from Lambert’s aggressive stance, Formosus later shifted his support to Arnulf of Carinthia, inviting him to invade Italy and claim the imperial crown. This invitation to Arnulf, a rival to Lambert, marked a significant change in Formosus’ political strategy and alliances. The consequences of these political maneuvers were far-reaching. Lambert and his mother, Agiltrude, gained considerable influence in Rome.

Reassessment of Motivations

Historical perspectives on Formosus’ actions and motivations have evolved. Initially, Formosus was often depicted as a staunch pro-Carolingian supporter, and his crowning of Lambert was seen as a coerced decision. However, contemporary scholarship has reevaluated this view, suggesting a more nuanced understanding of his political engagements.

Recent interpretations propose that Formosus did not exclusively support the Carolingian faction but maintained a more balanced and pragmatic approach to his political relationships. Evidence suggests that he had friendly relations with Lambert until around 895. This shift in relations coincided with the aggressive expansion of Guy IV of Spoleto, Lambert’s cousin. Guy IV’s actions, particularly his march on Benevento and expulsion of the Byzantines, alarmed Formosus. This may have prompted him to seek assistance from Arnulf, indicating a strategic rather than ideological realignment.

The reassessment of Formosus’ motivations provides a clearer understanding of the complex and often shifting allegiances of the period. It also sheds light on the factors leading to the Cadaver Synod, illustrating that it was not merely a religious proceeding but a culmination of political tensions and conflicts that had been brewing for years. This perspective underscores the interplay between religious authority and secular power during a tumultuous period in medieval European history.


Cadaver Synod held in January 897

Cadaver Synod held in January 897

Exhumation and Trial of Formosus’ Corpse

The actions taken by Pope Stephen VI against the deceased Pope Formosus in the Cadaver Synod were extraordinary and unprecedented in the history of the Catholic Church. Stephen VI, driven by motivations that remain a topic of historical debate, ordered the exhumation of Formosus’ body nearly seven months after his death. This decision to posthumously try a former pope was not only unusual but also deeply symbolic, reflecting the intense political and ecclesiastical rivalries of the time.

The Charges Against Formosus

During the trial, a deacon was appointed to represent Formosus, speaking on behalf of the corpse that was propped up on a throne in a grotesque mimicry of a living defendant. The charges leveled against Formosus were serious and multifaceted. Firstly, he was accused of violating canon law, specifically the law that prohibited a bishop from leading more than one diocese. This accusation was likely linked to his earlier appointment in Bulgaria and his later roles as Bishop of Porto and Pope.

The second charge, perjury, might have stemmed from the oath Formosus was rumored to have taken at the Council of Troyes, promising to remain a layman and refrain from seeking ecclesiastical office. His subsequent return to ecclesiastical roles, culminating in his papacy, would have constituted a breach of this oath if it indeed occurred as reported.

Lastly, the charge of serving as a bishop while technically a layman was related to the earlier allegations and was a grave offense in the context of ecclesiastical law and tradition. The notion that Formosus had ascended to the highest religious office in the Christian world while being technically a layman (due to his supposed oath) would have been seen as a serious affront to the Church’s integrity and rules.

The Mock Trial and Representation

The trial, steeped in ecclesiastical and political intrigue, concluded with the posthumous conviction of Formosus. This conviction was not just a symbolic gesture; it had tangible repercussions. The corpse of Formosus was desecrated in a series of acts that were both shocking and indicative of the intense animosity towards him. His papal vestments were removed, the three fingers on his right hand, used for blessings, were cut off, and all his papal decrees and ordinations were invalidated. This act of desecration was a clear message, denouncing Formosus’ entire papacy and erasing his influence from the church’s history.

Disposal of Formosus’ Body

Finally, the body of Formosus was disposed of in a manner devoid of any dignity or respect. It was initially buried in a common grave for foreigners, only to be later exhumed again, tied to weights, and cast into the Tiber River. This final act of discarding his body in the river was symbolic of completely erasing his legacy and presence from the church and was a stark testament to the brutal politics of the era. 


Public Outcry and Stephen VI’s Downfall

The Cadaver Synod, with its macabre and grotesque proceedings, provoked a strong backlash from the public and the clergy. The vivid imagery of a deceased pope being put on trial caused widespread horror and indignation. This shift in public opinion was a major factor in the eventual downfall of Pope Stephen VI. He was deposed, imprisoned, and later met a violent end, mirroring the brutal nature of the synod he had orchestrated.

Reversal of the Synod’s Decisions

In the wake of the Cadaver Synod, subsequent popes sought to rectify the injustice and restore the Church’s moral standing. Pope Theodore II, shortly after his election, convened a synod that nullified the rulings of the Cadaver Synod. This act was a significant step towards rehabilitating Formosus’ legacy. Similarly, Pope John IX also condemned the Cadaver Synod and reaffirmed the actions taken by Theodore II, further solidifying the Church’s stance against the Synod’s rulings.

Restoration of Formosus’ Dignity

Both Theodore II and John IX played crucial roles in restoring the dignity and honor of Pope Formosus. His body, which had been subjected to such indignity, was recovered and reburied in Saint Peter’s Basilica with full papal honors, symbolically undoing the desecration it had suffered.

Continuing Controversy Under Sergius III

However, the controversy surrounding Formosus did not end with these restorative actions. Pope Sergius III, who had been a co-judge in the original Cadaver Synod, ascended to the papacy and took the unprecedented step of reaffirming the convictions against Formosus. This act reopened old wounds and underscored the ongoing political and ideological rifts within the church.

Legacy of the Cadaver Synod

The Cadaver Synod remains one of the most notorious and sensational events in the history of the Catholic Church. It is frequently cited as an example of the extreme lengths to which ecclesiastical politics could go in the medieval period.

The Synod exemplifies the intricate and often volatile intersection of religious and secular power during the Middle Ages. It highlights how personal vendettas, political machinations, and theological disputes could converge in dramatic and sometimes disturbing ways.

Impact on Papal History and Church Policy

The events of the Cadaver Synod had lasting implications for the governance of the church. They prompted a reexamination of papal policies and procedures, particularly regarding the treatment of deceased popes and the conduct of ecclesiastical trials.

The Cadaver Synod also serves as a reminder of the human aspect of the papacy. It shows that popes, despite their spiritual authority, were not immune to the political struggles and personal animosities of their time. The Synod’s legacy continues to provoke discussion and analysis, serving as a cautionary tale about the dangers of allowing secular power struggles to infiltrate religious leadership.


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Source: (Study, 2019)


  • Study. (2019). The Cadaver Synod: Putting a Dead Pope on Trial ~ With Dr Gulker [YouTube Video]. In YouTube. https://www.youtube.com/watch?v=BLyTBMRWDCo

  • Wikipedia Contributors. (2023, November 24). Cadaver Synod. Wikipedia; Wikimedia Foundation. https://en.wikipedia.org/wiki/Cadaver_Synod

  • Moore, M. E. (2014). The Attack on Pope Formosus: Papal History in an Age of Resentment (875-897). In M. E. Moore, J. Maciejewski, & R. Kotecki (Eds.), Ecclesia et Violentia: Violence Against the Church and Violence Within the Church. Cambridge Scholars Publishing

  • Monroe, W. S. (2016, February 27). The Cadaver Synod and the End of the Carolingian Empire. Paper presented at the Medieval Academy of America Annual Meeting

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