The birthday of the emperor Maximian Herculeus was celebrated in the year 298, with extraordinary feasting and solemnity. Pompous sacrifices to the Roman gods made a considerable part of this solemnity. Marcellus, a Christian centurion or captain in the legion of Trajan, then posted in Spain, not to defile himself with taking part in those impious abominations, cast away his military belt at the head of his company, declaring aloud that he was a soldier of Jesus Christ, the eternal King.
He also threw down his arms and the vine-branch, which was the mark of his post of centurion; for the Roman officers were forbiddden to strike a soldier with any instrument except a vine-branch, which the centurions usually carried in their hands. The soldiers informed Anastasius Fortunatus, prefect of the legion, by whose order Marcellus was committed to prison. When the festival was over, this judge ordered Marcellus to be brought before him, and asked him what he meant by his late proceedings. Marcellus said, When you celebrated the emperor”s festival on the 12th before the calends of August.
(Source: The New Roman Missal, Rev. F. X. Lasance)