Originally published on Atlas Obscura.

The motto liberté, égalité, fraternité is all over Paris, from the walls of the Panthéon to the Hôtel de Ville. Yet that famous phrase of "liberty, equality, fraternity" omits a few words that were often included during the French Revolution: “ou la morte” — "or death."

Put that way, it might remind you of the Reign of Terror that swept through the ideals of the Revolution. But without it, the city’s violent history hides in plain sight. Despite reminders of the Revolution nearly everywhere you look, from mass graves from the guillotine at the Cimetière de Picpus to the stones of the Bastille reconstructed as the Pont de la Concorde, the one thing that can be hard to fathom in modern-day Paris, is the sheer terror of The Terror.

It’s perhaps most noticeably absent in Marie Antoinette’s cell at the Conciergerie. To Americans like me, the name alone suggests the Four Seasons instead of death row. In her cell, a mannequin serves as a stand-in for the queen, but she’s frozen in time, sitting in front of a tiny altar with her head eternally attached to her neck. It’s difficult to imagine the panic and dread she must of felt beneath her dignified façade on the way to the scaffold, but then again, being sympathetic and well-understood was never Marie Antoinette’s strong suit. Even the original site of the guillotine that decapitated her doesn’t inspire much fear today, transformed into the Place de la Concorde with its enchanting, illuminated obelisk.

But there’s at least one place where the violence of the French Revolution is still palpable. Every Saturday at 3 pm, you can take a guided tour of the crypt beneath St. Joseph des Carmes. There you can see the battered remains and bloodstains of some lesser-known victims of The Terror — a group collectively known as the martyrs of September.

The martyrs were a group of priests, seminarians, bishops, and, most famously, the Archbishop of Arles. They were rounded up by a mob of sans-culottes and imprisoned in the convent near St. Joseph's after refusing to take an oath that undermined papal authority. The mob’s punishment for this transgression was quick and especially brutal. They began killing their prisoners on September 2, 1792, when they bashed in the Archbishop’s head, stabbed him, and trampled the body.

The following day the mob set up a kangaroo court to try the remaining prisoners. Martyrologist John Foxe described them as soaked in blood up to the elbows with executioners and judges freely subbing in for one another without bothering to wipe the gore off their hands.

Unsurprisingly, nearly all the clergy members were found guilty. But instead of condemning them from the bench, the judges simply told them they were free to leave. Each defendant left down the same stairway and at the bottom there were plenty of people waiting to hack their bodies apart. British ambassador, Earl Gower,described the wake the mob left behind:

“After [the killings] their dead bodies were dragged by the arms or legs to the Abbaye… here they were laid up in heaps till carts could carry them away. The kennel was swimming with blood, and a bloody track was traced from the prison to the Abbaye door where they had dragged these unfortunate people.”

When it was over, 190 people were killed at the convent in just two days. Their bodies were thrown in a pit and covered in quicklime.

Today, some of the recovered bones of the martyrs are on display in the church crypt. Many still have the obvious marks of swords and pikes. Some skulls sit in niches, while others are stacked in a cabinet above the epitaph, "Having preferred death to violating the holy law of God, they were massacred." In a separate room, bloodstained paving stones are displayed. The spilled blood, coupled with the list of names of the martyrs and the portraits of the executed bishops, allows us an unusually visceral, yet empathetic look at these casualties of the Terror. 

Of course there are other, less shocking monuments to the Martyrs of September. Every day at nearby Saint-Sulpice, visitors pass a memorial featuring two black angels without knowing the story behind it. There, The Terror continues to hide in plain sight. 

(Special thanks to Marie-Christine Pénin for her photos of the crypt. See more at www.tombes-sepultures.com. Engraving: "The Massacre Of The Priests In September 1792" by Hippolyte de la Charlerie, photo of the memorial to the Martyrs of September by Allison C. Meier)