Gervase and Protase, Martyrs

Today we commemorate Gervase and Protase. According to Butler:

ST. AMBROSE calls these saints the protomartyrs of Milan. They seem to have suffered in the first persecution under Nero, or at latest under Domitian, and are said to have been the sons of SS. Vitalis and Valeria, 1 both martyrs, the first at Ravenna, the second at Milan. This latter city was the place which SS. Gervasius and Protasius rendered illustrious by their glorious martyrdom and miracles. St. Ambrose assures us, that the divine grace prepared them a long time for their crown by the good example which they gave, and by the constancy with which they withstood the corruption of the world. He adds they were beheaded for the faith. 2 They are said to have been twin brothers.