La Force Prison, originally a private mansion in the Marais district of Paris, was converted into a prison in the early stages of the French Revolution. This prison became particularly notorious during the Reign of Terror. Its history offers a glimpse into the chaotic and often violent atmosphere of revolutionary Paris. The transformation of La Force Prison began in 1780 when financier Henri Jacques Nompar de Caumont, Duc de La Force, sold his property to the government. By 1785, the French authorities had decided to convert the buildings into two adjacent establishments: La Grande Force and La Petite Force. The former housed male prisoners, while the latter was designated for female detainees. La Force Prison was known for its overcrowding and harsh conditions. The cells were small and often housed multiple prisoners. The hygiene was abysmal, with limited access to clean water and proper sanitation. These conditions became more pronounced as the Revolution progressed, particularly during the intense political purges of the Reign of Terror (1793–1794). In September 1792, La Force became infamous during the September Massacres, a series of killings that targeted prisoners believed to be counter-revolutionaries. Over 1,000 prisoners were killed across Paris, with La Force witnessing a significant share of the bloodshed. The most significant victim was Princess Marie Louise de Lamballe, a close confidante of Queen Marie Antoinette. Her brutal murder and mutilation shocked Paris and was reported extensively throughout Europe. Imprisonment at La Force was often arbitrary, with many individuals detained on mere suspicion of opposing the revolution. The National Convention, heading the revolutionary government, facilitated mass arrests. This contributed to the prison’s overcrowded conditions, with many detainees awaiting trial or execution by the guillotine. Famed prisoners included writers, political figures, and ordinary citizens. Among them was poet André Chénier, who was detained at La Force before being executed in the closing days of the Reign of Terror. The imprisonment of well-known figures highlighted the Revolution’s indiscriminate nature when it came to dealing with perceived enemies or dissenters. La Force Prison continued to serve as a detention facility after the Revolution, though it never regained the same level of infamy it had during the earlier years. It remained in use until it was demolished in the mid-19th century. The history of La Force Prison continues to demonstrate the tumultuous and often ruthless nature of the French Revolution’s justice system.