The Martyrdom of St Erasmus is the first public work of Nicolas Poussin in Rome, where the French painter had arrived in 1624. Painted for the altar of the right transept of St Peter's Basilica in which the relics of the Saint are preserved, the painting remained there until the eighteenth century when it was replaced by a copy in mosaic and transferred to the pontifical palace of the Quirinal. Brought to Paris in 1797 following the Treaty of Tolentino, after its return, it became part of the Vatican Art Collection of Pius VII (1820).
The altarpiece, the commission for which was initially given to Pietro da Cortona, passed in 1628 to Poussin, who completed it by the following year, following the preparatory sketches already made by Cortona.
The painting shows Erasmus, bishop of Formia, while he suffers martyrdom during the persecutions of Diocletian in 303 A.D.
The painter portrays the martyr in the foreground, a priest who indicates the statue of Hercules (the pagan idol that Erasmus had refused to worship and for this suffered martyrdom in the public square), a Roman soldier on horseback charged with the execution, the executioner who extracts the intestines rolling them around a sailor's capstan, a fragment of classical architecture and angels that descend towards the victim bringing the palm and crown, symbols of martyrdom. This composition became an actual prototype for the subsequent portrayals of episodes of martyrdom and Valentin also took inspiration from it for his Martyrdom of St Processo and St Martiniano painted for a nearby altar in St Peter's.