The cross of the early Christian emperors was a labarum or token of victory in war, a standard for use in battle.
The labarum was the official standard of the Emperor of Rome, and upon it were displayed the "insignia" of the emperor of the day.
One would imagine from all this that there was only one labarum.
labarum, lab′a-rum, n. a Roman military standard adopted as the imperial standard after Constantine's conversion.
The safety of the labarum was entrusted to fifty guards of approved valour and fidelity.
The fetichism connected with the cross probably took its rise from the labarum.
The age that could accept such a prodigy, of course found no difficulty in the vision of Constantine and the story of the labarum.
He received it, notwithstanding the labarum, and received further the title of Pontifex Maximus, which he retained all his life.
The labarum, which was the imperial standard of later emperors, resembled in shape and fixing the vexillum.
This standard was known by the name of the labarum—a word the etymology of which is very uncertain.