The Episcopal Catalogue of Aquileia lists Hermagoras as the first of the Aquileian bishops. According to a legend St. Mark was ordered by St. Peter to go as a missionary to Aquileia and subsequently Hermagoras was chosen by the Evangelist for that mission. These are the reports written by Paul the Deacon and Paulinus of Aquileia at the end of the eighth century. The iconography involving Hermagoras depends on these traditions that were generally considered as true until the beginning of the twentieth century: he is displayed next to St. Mark (in the fresco on the apse of the patriarchal basilica of Aquileia that dates back to 1031) or consecrated by St. Peter (fresco of the year 1160 circa in the crypt of the same basilica), where he is shown with the crosier that was to be repeated as a sign of distinction of the patriarchal authority and would be called ‘St. Mark’s crosier’, even though it is not datable to earlier than the eleventh century. The oldest documents never put Hermagoras beside St. Mark: the evangelist’s name, on the contrary, regularly follows the name of Fortunatus. A systematic and regular inclusion of the two saints in the same worship and in the liturgy of Aquileia occurs in the passage from the eighth to the ninth century: Paul the Deacon reports that St. Peter had sent Mark to Aquileia and appointed Hermagoras head of the community of Aquileia. A diploma issued by Charlemagne on 4 August 792 attests that the basilica of Aquileia had been built in honour of St. Mark; but another diploma, issued on that same day, adds also the name of Hermagoras for the same church. In St. Euphemia’s at Grado the name of Hermagoras appears in a pergula tympanum erected by the patriarch Vitalis II (just before 900); more important in that same basilica it is the pergula architrave with the name of St. Mark that dates to the time of the patriarch Fortunatus II and the anti-patriarch Iohannes Iunior (807-810), which is the oldest epigraphic witness of the Evangelist’s worship in the high Adriatic area. In the Episcopal Catalogue Hermagoras is already called «patriarcha»: this title was likely due to St. Mark’s legend and it was accordingly attributed to the bishops of Aquileia a good deal before the sixth century, when it was denied by pope Pelagius I.
The name of the martyr Fortunatus occurs on August 14th together with Felix in Jerome’s Martyrology: by the end of the fourth century Chromatius appreciated these two martyrs since he was convinced of their Aquileian provenance. As early as the fifth century, at least, a basilica was dedicated to them in the south of Aquileia, and another one at Vicenza.
For further information see the entry Ermagora e Fortunato, santi written by Sergio Tavano, in Nuovo Liruti, Dizionario biografico dei Friulani, 1, Il Medioevo, edited by C. Scalon, Udine, Forum, 2006, 301-306.