I found little information about St Cerbasius, except that he was a Martyr of one of the Pagan Roman Persecutions. Most probably, he died in the razzias undertaken by Maximian, who was the most vicious executor during the Great Diocletian Persecution. Maximian ruled Italia, Africa, and Hispaniae from Mediolanum (modern Milano); as Ravenna was nearby, it meant that the area probably suffered more than usual, due to its geographical propinquity to an imperial capital (which was no longer Roma by the late third century). Conversely, foxy Bishop Mensurius of Carthage was aided in his successful deceptions by the fact that his city was far away from the imperial court, at the extreme southern limit of Maximian’s territories), so, his pagan magistrate friend (were they old school chums?) didn’t feel so pressured to conform exactly to the letter (let alone the spirit) of Maximian’s decrees.