The Early See of Ravenna
By the local tradition of Ravenna, the church there was founded by the Apostle Apollinaris, sent from Antioch and honored as the city's first bishop. He was followed by Adheritus (Aderitus) and then by Eleuchadius, remembered as a Greek philosopher who embraced Christianity and who is reckoned the third bishop, serving until about 112. Marcian appears in the traditional succession immediately after Eleuchadius, placing him among the founding generation of hierarchs of the see.
The historical reliability of these earliest dates is uncertain. The episcopal succession was transmitted by Agnellus, writing in the ninth century from a list said to derive from an earlier bishop, and historians have noted that the chronology of the first bishops of Ravenna cannot be securely fixed. Working back from the better-attested attendance of a later bishop of Ravenna at the Council of Sardica in 343, some scholars place the founding of the see toward the end of the second or the beginning of the third century. The conventional dates for Marcian's episcopate should therefore be read as part of this traditional reckoning rather than as firmly documented history.