In the late 1700s, gold output in Minas Gerais declined while the Portuguese Crown kept demanding fixed levels of revenue. Officials threatened a derrama (a forced collection to make up tax shortfalls), increasing tension between the colonial government and local elites. These conditions helped set the stage for republican plotting in the captaincy.
A group of miners, landowners, clergy, and educated professionals in Minas Gerais began discussing breaking with Portugal and forming a republic. Their plans drew on Enlightenment ideas and examples such as the United States. The expected derrama was treated as a trigger for action, but the plot depended on secrecy and coordination among many participants.
Joaquim Silvério dos Reis informed the governor of Minas Gerais, Viscount of Barbacena, about the conspiracy. According to later accounts, he sought relief from debts and other benefits in exchange for information. This denunciation gave colonial authorities a starting point for arrests and a broader investigation.
Other denunciations followed, strengthening the case that a coordinated political conspiracy existed in Minas Gerais. These reports increased pressure for a formal inquiry and helped authorities identify suspects beyond the first names mentioned. The flow of information from insiders made it difficult for the movement to proceed.
Joaquim José da Silva Xavier—known as Tiradentes—was arrested in Rio de Janeiro as the plot unraveled. His detention became the most famous case from the conspiracy, in part because he later received the harshest punishment. The arrest marked a clear turning point from secret planning to state repression.
Portuguese officials launched a devassa, a major judicial investigation used in the Portuguese monarchy for serious crimes, including treason. The inquiry collected testimonies, seized books and papers, and built a legal case against suspected conspirators. This process turned political suspicion into a long-running court proceeding.
Over many months, the devassa produced detailed records of interrogations and property seizures. Authorities targeted both well-connected local figures and lower-ranking participants, treating the affair as a threat to royal authority. The growing documentary record became the foundation for later sentencing decisions.
After years of investigation and proceedings, the court sentenced multiple conspirators—some to death and others to exile. These rulings showed that the Crown wanted to discourage future separatist organizing without necessarily executing everyone involved. The sentencing phase shifted the case from investigation to punishment.
Royal authorities commuted the death sentences of most condemned conspirators, replacing them with banishment, including exile to Africa for several. This reduced the number of executions while still imposing severe penalties and removing key figures from Minas Gerais. Tiradentes remained the main exception.
Tiradentes was publicly hanged in Rio de Janeiro and his body was cut into pieces as a warning. He became the only conspirator executed, while others were exiled or otherwise punished. The execution helped transform the failed plot into a powerful later symbol of anti-colonial resistance.
The Inconfidência Mineira left an unusually extensive paper trail in the Autos da Devassa, preserving testimonies, accusations, and legal reasoning from the Crown’s investigation. These records became central for later historians studying late-colonial politics, Enlightenment influence, and Portuguese legal practices in Brazil. The documentation also shaped how different participants were remembered.
Long after the plot failed, Tiradentes’ image was adopted by later Brazilian republican and nationalist memory as an early symbol of independence. His execution date became widely commemorated, linking the late-colonial conspiracy to broader narratives of Brazilian nationhood. This legacy marked a lasting outcome: a defeated movement gained long-term political meaning through public remembrance.
Inconfidência Mineira and late-colonial republican plots (1788–1792)