As you probably know, St. Peter’s in Rome is built over a good chunk of Nero’s circus, a racetrack inside Nero’s Golden House’s extensive parklands. Nero had St. Peter and many other Christians crucified on the racetrack, while others were set along the paths in the park. Those that lived until dusk were doused with oil and set on fire, as temporary streetlights for the park.
Christians went to a lot of trouble to retrieve the bodies of their martyrs and bury them reverently, often with the help of secret Christians, pagan sympathizers (burying the dead was also a pagan virtue, as seen in the Greek tragedy Medea) or those who could be bribed to help.
However the Christians retrieved St. Peter’s body, they got him, and buried him in a pagan cemetery that stood very close to the walls of Nero’s park, conveniently close to the racetrack. The presence of his tomb seems to have been an open secret in the Christian community, with centuries of pious graffiti left inside the tomb along with some kind of small prayer chapel for visitors, but the outside unmarked. Baptisms seem to have been conducted nearby. But apparently it was a secret to the pagan Roman authorities, and to the pagan tomb owners nearby.
However, during Diocletian’s persecution of Christians, the secret seems to have gotten out.
The backstory involves St. Sebastian. As the story goes, when he joined the Roman army as a young man, he was already a Christian. He kept a low profile of his Christianity, but helped other Christians whenever he could. At one point in his early career, under the reign of Emperor Carinus (who was the son of Emperor Carus, who had just died on campaign in Persia, and who was fighting for the throne with Emperor Diocletian, who was still out east), he made it his business to visit and encourage Marcellianus and Marcus, two Christians who were imprisoned in Rome and due to be martyred. (They were converted pagans, twin brothers who became deacons to the Pope. Needless to say, twin brother saints were very important in the city of Rome.)
But during the course of his visits to the prisoners, he had made friends with the prison staff, including Nicostratus, the chief secretary in charge of keeping tabs on the prisoners, and his wife Zoa, who had a “tongue palsy” that prevented her from speaking; and Claudius, the jailer and notary in charge of Marcus and Marcellianus.
Zoa happened to be listening when Sebastian gave the potential martyrs a particularly fiery and encouraging talk about not losing their courage and lapsing from Christianity. She was so moved that she fell down at Sebastian’s feet, longing to be Christian. Sebastian made the Sign of the Cross in front of her mouth, and her tongue was cured, and she spoke and thanked God.
St. Sebastian’s friends converted to Christianity, along with Martia/Marcia and Tranquillinus, the pagan parents of Marcus and Marcellianus (who had been urging them to be sensible and make sacrifices to the emperor’s genius); and sixteen other prisoners who had been there. Then Nicostratus brought the new converts, including the prisoners, to his own quarters (which would have been inside the prison) to rest up, and Sebastian sent for a priest named Polycarp to instruct the converts in Christianity and then baptize them.
When Marcus and Marcellianus’ father, Tranquillinus, was baptized, he was also instantly cured of gout. Somehow, the Roman city prefect, Agrestius Chromatius, heard about this — and he had horrible gout also. He sent for Sebastian and was cured. So he demanded baptism for himself and his son Tiburtius. Chromatius, who had persecuted Christians, used his authority to refuse to prosecute, and freed all the prisoners (including Marcus and Marcellianus). He followed this up by freeing all his slaves by using a fair portion of his wealth to manumit them, and then resigned from the prefectship.
This was in about 283. In 285, Emperor Carinus was defeated in battle by Emperor, Diocletian. Diocletian met Sebastian at some point and put him in charge of some of the Praetorian Guards. Diocletian left Italy but left behind his adopted heir and buddy, Maximian, and Sebastian served as a Praetorian Guards commander for him, too.
Chromatius, having been associated with Emperor Carinus, did the smart thing and got Diocletian’s permission to retire to his estates in Campania. He took a lot of Christians with him, to work there as free persons. Fr. Polycarp also went along.
Persecutions had continued under Diocletian, initially without much impetus from above or new laws. The big persecutions wouldn’t even start until 299, when pagan haruspices famously blamed their failure to be able to read the entrails on the presence of Christians in the imperial household. So what would happen next was pretty much politics.
Maximian, Diocletian’s old battle-comrade, trusted best friend, and imperial heir, was supposed to get the West under control. He sent a subordinate named Carausius (who was probably from Britain and seems to have a British name) to go deal with the pirates on Britannia’s Saxon Shore. Carausius glommed onto the pirate goods himself. Maximian tried to get him arrested, but Carausius revolted and named himself co-emperor, of Britannia. So on April 1, 286, Maximian named himself co-emperor of Diocletian.
At this point, local persecution in Rome greatly increased. Christians refused to sacrifice to the emperors, so Christians were traitors to Maximian. Obviously Maximian was a bit nervous about his emperor status, even though Diocletian ended up agreeing and understanding.
Pope Caius stayed in town, but he agreed for himself and his deacons to be moved to a secure area that the pagan authorities would never guess — the imperial palace in Rome, in the rooms of a Christian chamberlain, Castulus.
On June 27th or 28th, 286, Nicostratus and Claudius, along with Castorius, Victorinus, and Symphorianus, were part of a group of Christians who went to retrieve bodies of martyrs and were caught. The magistrate left them in prison for ten days, trying to get them to make a sacrifice to the emperors.
On June 29th, 286 (that’s the feast of Ss. Peter and Paul), St. Zoa was arrested for being a Christian — while praying at St. Peter’s tomb, in the confessio chapel inside it. (Probably for her husband and the rest of the guys.) She was thrown into prison, where she was apparently kept in the dark as an extra torture or punishment. On July 5th, she was executed by being tied to a tree by the throat and by the hair, or by being dangled from the tree after being tied there by her feet. Either way, she was smothered by noxious smoke from a fire at the foot of the tree.
Tranquillinus apparently was still sensitive about the courage thing and about encouraging his sons to be cowards; so he went to pray at the tomb of St. Paul (now St. Paul Outside the Walls). He got caught by a mob of pagans, and was stoned to death. (A lot of normal ordinary pagans blamed Christians for misfortunes, because obviously the gods were angry at Christians for not worshipping them.)
On July 7, 286, Nicostratus, Claudius, Castorius, Victorinus, and Symphorianus were all taken out to Ostia, taken out to sea in a boat, and dropped overboard. They drowned. (There was a lot more of this kind of execution under Galerius, including of people who didn’t pony up enough taxes. At least once, they just sank the whole boat along with all the prisoners stuffed on board.)
Castulus and Tiburtius were turned in by a supposed Christian, Torquatus, who turned on them. As a Roman citizen, Tiburtius was beheaded and suffered no torture, but Castulus was tortured and then buried alive in a sand pit on the Via Labicana. Probably thanks to Castulus’ silence under torture, Pope Caius and his other deacons got away; Caius didn’t die until 296. (He was a Dalmatian like Diocletian, and some say they were relatives. Not that Diocletian didn’t kill a lot of relatives.)
Marcus, Marcellianus, and Sebastian were all sentenced to be tied to a post and then shot to death with arrows. But when Castulus’ widow, Irene, showed up to sneak out the bodies, she found that Sebastian was just barely alive. She took him to where she was staying and nursed him back to health; but then, on January 20, 288, Sebastian snuck out and went to greet the emperor at a stairwell that he had to pass as part of his normal day, and then reproached him for being unjustly cruel to Christians.
So the emperor (not relying on the Praetorians, and you can’t blame him) had his normal Roman nobleman entourage of club-carrying slaves grab Sebastian and beat him to death. As one does. And then throw his body into the Cloaca Maxima storm sewer. As one does.
But the Christians still managed to retrieve Sebastian’s body. As one does. A pious Christian woman of means named Lucina dreamed that a martyr was telling her to go get the body, and where it was; and the dream was right. She buried the body in the catacombs, and the church of St. Sebastian was later built over it.
Some say that Irene lived on, while others that she was martyred in 288. Chromatius is also said to have been martyred, but nobody seems to know the details. The priest Polycarp is called “blessed” in the Roman Martyrology.
The Acts of St. Sebastian are ancient, but of course there’s no way to prove that they’re true or not true. Except that lots and lots of these saint names were given to other Christians, right after the persecutions, and the Church of St. Sebastian is ancient too. (There was also a basilica of Ss. Marcus and Marcellianus in the catacombs of St. Balbina; it was rediscovered in 1902.) So it seems likely to me that all the days and general facts are probably true. It’s more likely that the emperor who killed Sebastian was Maximian, rather than Diocletian; but that’s about it. Maximian was away fighting on the Rhine during 287, so that makes sense of why Sebastian would make his move in the winter of 288.
So here are the saints’ days:
January 20: St. Sebastian, martyr
March 26/27: St. Castulus, martyr
April 3: St. Irene, holy woman
April 22: Pope St. Caius, confessor
June 18: Ss. Marcus and Marcellianus, martyrs
July 5: St. Zoa or Zoe, holy woman, martyr
July 7: Ss. Nicostratus, Claudius, Castorinus, Victorinus, and Symphorianus, martyrs
August 11: Ss. Tiburtius and Chromatius, martyrs