Relic of the chains of St Peter

San Pietro in Vincoli, Rome 

An entry in the Roman Martyrolgy under 1st August reads: “At Rome, on the Esquiline, the dedication of the church of St Peter in Chains (i.e. San Pietro in Vincoli, Rome)”.

San Pietro in Vincoli

Two inscription that are known from copies record that

1. ✴that Philipus (who is documented in 431 as “presbyter of the Congregation of the Apostles”) had rebuilt the church and was subsequently responsible for it;
   

2. ✴that the rebuilding was in fulfilment of a vow made by the Emperor Theodosius II, together with his wife Eudocia and his daughter Eudoxia; and
   

3. ✴that it was consecrated by Pope Sixtus III (432-40) and given a new dedication to SS Peter and Paul.
   

Theodosius II was the emperor in the east: Eudoxia married Valentianian III, the emperor in the west, at Constantinople in 437.  It seems (since Valentinian III is not mentioned in the inscription) that Theodosius II had financed the rebuilding.  Eudoxia probably represented him at the consecration during her first visit to Rome in 439-40.

From 431, the church is usually documented officially as “ecclesia Apostoloum”.  The first recorded use of the title “a vincula sancti Petri Apostoli” dates to 501.  However, this seems to have been its popular name: the official dedication to the Apostles was maintained until the 8th century.  Richard Krautheimer (see below) suggests that the original church had been built in ca. 420 and that its original dedication had been to St Peter alone.

Chains of St Peter

According to legend, the Empress Eudocia had brought the chains used in the first imprisonment of St Peter from Jerusalem to Constantinople.  In fact, while she was indeed in Jerusalem in 438 and again in 440-61, there is no contemporary reference to any such translation.  The legend continues that her daughter, the Empress Eudoxia gave these chains to Pope Leo I (440-61), and that when he compared them to the chains from St Peter's later imprisonment in Rome, the two chains miraculously fused together.

The earliest surviving reference to the relic of the chains of St Peter is in the epitaph (known from copies) in San Pietro, Spoleto of Bishop Achilleus.  The epitaph says that he had built the church and that it contained “vincla petri”.  Bishop Achilleus celebrated Easter in Rome in 419, and it is usually assumed that he obtained filings from the relic at that time. 

This suggests that a relic of the chains of St Peter was already in the church that was rebuilt  and dedicated to the Apostles in 431, which, as noted above:

1. ✴had originally been built in ca. 420 and dedicated to St Peter; and
   

2. ✴which was popularly known, at least from 501, as San Pietro in Vincoli (or variants thereof).