Their Witness
The Orthodox synaxarion summary records that Hermes, Serapion, and Polyaenus distinguished themselves by their zeal in spreading the faith and in answering the polemics of the pagans. They were subsequently arrested and brought before the authorities, where they remained firm in their profession of faith and so suffered martyrdom.
The Roman Martyrology, in its entry for August 18, names 'the holy martyrs Hermas, Serapion, and Polyaenus' and states simply that they suffered death at Rome for the faith. A traditional detail preserved in that source relates that, being dragged through narrow, stony, and craggy places, they yielded up their souls to God. Some sources give the first name as 'Hernias' rather than 'Hermes,' reflecting variation in the manuscript tradition.
A Question of Date and Identity
The historical notices for these three martyrs are sparse, and reference works caution that nothing in them provides reliable detail about the precise circumstances or timing of the martyrdoms. The New Advent Catholic Encyclopedia raises the possibility that the August 18 group may in fact be identical with martyrs commemorated on August 28.
The August 28 commemoration honors a Roman martyr named Hermes, buried in the catacomb of Hermes and Basilla, together with the Alexandrian martyrs Polienus and Serapion. On this theory, the appearance of the same three names under the earlier August date could have arisen from a simple clerical transposition of the Roman calendar notation — XV instead of V Kal. Septembris. The Encyclopedia cites the Acta Sanctorum, the Martyrologium Hieronymianum, and various ecclesiastical calendars of Constantinople and the Eastern Church in connection with the question, which remains unresolved.