Labarum, the military standard of Constan-tine the Great, adopted by him in commemoration of the appearance of the cross in the sky when he was on the march against Maxentius. It consisted of a pole or pike with a horizontal bar forming a cross, from which depended a square purple banderole, ornamented with fringes and precious stones. The staff was surmounted by a golden crown set with jewels, in the midst of which was the monogram of Christ, with the occasional addition in later times of the Greek letters alpha and omega. On medals of Valentinian I. it is represented without the crown and with the monogram on the banderole; and sometimes the figure of Christ was displayed on the latter. Prudentius says that "Christ, woven in jewelled gold, marked the purple labarum." Julian the Apostate removed the sacred symbols and substituted for them the ancient S. P. Q. R., but Jovian restored them. The origin of the word is involved in obscurity, and scholars are undecided when it was first applied to the Roman standard; but it is found on coins and medals of the first emperors, especially on those connected with the Germanic and Armenian wars.

Under the pagan emperors the ensign usually bore the image of the emperor or that of Jupiter, Mars, or Mercury.

Labarum, from a Medal of Valentinian I.

Labarum, from a Medal of Valentinian I.